The Experts below are selected from a list of 9 Experts worldwide ranked by ideXlab platform
Robert Tjian - One of the best experts on this subject based on the ideXlab platform.
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molecular cloning and functional analysis of drosophila TAF110 reveal properties expected of coactivators
Cell, 1993Co-Authors: Timothy Hoey, Robert O J Weinzierl, Grace Gill, Jinlong Chen, Brian David Dynlacht, Robert TjianAbstract:The general transcription factor TFIID is a multiProtein complex containing the TATA-binding Protein and several associated factors (TAFs), some of which may function as coactivators that are essential for activated, but not basal, transcription. Here we describe the isolation and characterization of the first gene encoding a TAF Protein. The deduced amino acid sequence of TAF110 revealed the presence of several glutamine- and serine/threonine-rich regions reminiscent of the Protein-Protein interaction domains of the regulatory transcription factor Sp1 that are involved in transcription activation and multimerization. In both Drosophila cells and yeast, TAF110 specifically interacts with the glutamine-rich activation domains of Sp1. Moreover, purified Sp1 selectively binds recombinant TAF110 in vitro. These findings taken together suggest that TAF110 may function as a coactivator by serving as a site of Protein-Protein contact between activators like Sp1 and the TFIID complex.
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lkdecular Cloning and Functionai Anatysis of0 ila TAFI 10 Rev& Expec4ed of Coactiiators
1993Co-Authors: Timothy Hoey, Grace Gill, Jinlong Chen, Brian David Dynlacht, J. Weinzierl, Robert TjianAbstract:Timothy Hoey, Robert 0. J. Weinzierl, Grace Gill, Jin-Long Chen, Brian David Dynlacht, and Robert Tjian Howard Hughes Medical Institute Department of Molecular and Cell Biology University of California at Berkeley Berkeley, California 94720 Summary The general transcription factor TFIID is a multiProtein complex containing the TATA-binding Protein and sev- eral associated factors (TAFs), some of which may function as coactivators that are essential for acti- vated, but not basal, transcription. Here we describe the isolation and characterization of the first gene en- coding a TAF Protein. The deduced amino acid se- quence of TAFllO revealed the presence of several glutamine- and serinelthreonine-rich regions reminis- cent of the Protein-Protein interaction domains of the regulatory transcription factor Spl that are involved in transcription activation and multimerization. In both Drosophila cells and yeast, TAFl 10 specifically inter- acts with the glutamincrich activation domains of Spl . Moreover, purified Spl selectively binds recombinant TAFllO in vitro. These findings taken together sug- gest that TAFllO may function as a coactivator by serving as a site of Protein-Protein contact between activators like Spl and the TFIID complex. Introduction How do sequence-specific DNA binding factors communi- cate with the transcriptional machinery to regulate rates of transcriptional initiation? A model that has gained increas- ing acceptance proposes that site-specific transcriptional activators and repressors interact directly with one or more of the accessory Proteins that form the initiation complex assembled at the promoter (for reviews see Gill and Tjian, 1992; Roeder, 1991). It is, at present, unknown whether ail RNA polymerase II regulatory factors work via a common mechanism during the assembly of an active initiation complex or whether different transcriptional activators function by interacting with different target Proteins in the initiation complex. To study the mechanisms involved in transcriptional control, the specific components required to assemble an activated transcriptional complex must first be biochemically defined. In recent years, aconcerted effort has been devoted to the purification, characteriza- tion, and subsequent molecular cloning of the genes en- coding all of the components of the transcription machin- ery for RNA poiymerase Ii (TFIIA, B, D, E, F, and H; for review see Zawei and Reinberg, 1992). These studies have, in some instances, revealed unexpected results that have profoundly altered our view of how activation of tran- scription occurs. For example, the cloning of the TATA- binding Protein (TBP) gene led to the finding that TFIID is not a single Protein, as had been generally assumed. Instead, in higher eukaryotes, TFIID consists of a multisub- unit complex containing the TBP and at least seven distinct and tightly associated factors, called TAFs (Dynlacht et al., 1991; Tanese et 1991). An important property of TAFs is that they are essential for mediating regulated transcription but are not required for basal activity. Thus, TAFs have the biochemical activi- ties expected of coactivators (Dynlacht et al., 1991; Tanese et al., 1991). It is not known how TAFs or coactiva- tors function to mediate regulated transcription, nor is it known whether ail TAFs serve as coactivators. In the sim- plest model, we originally proposed that coactivator pro- teins could serve as adaptor molecules connecting the activation domains of regulatory factors and the basal tran- scriptional machinery (Pugh and Tjian, 1990), and we speculated that perhaps different classes of activators have different coactivator requirements. Studies in yeast have identified an activity, termed a mediator or adaptor, that may function as a bridging Protein between the tran- scriptional activator VP16 and the basal factors there- fore may be similar to coactivators (Berger et al., 1990; Kelleher et al., 1990; Flanagan et al., 1991). Unlike TAFs, the adaptor or mediator Proteins in yeast do not appear to be stably associated with TBP, which can be purified from yeast as a free Protein (Buratowski et al., 1988). Eukaryotic transcription factors have a modular design with separable DNA-binding and activation domains (for review see Frankel and Kim, 1991). Transcriptional activa- tion domains can be thought of as those parts of regulatory factors that are specialized for Protein-Protein interaction with some component of the transcription initiation com- plex. Transcriptional activation domains are typically di- vided into three major classes based on their amino acid sequences: those rich in acidic, glutamine, or proline resi- dues (for review see Mitchell and Tjian, 1989). It is, at present, unknown whether these classifications reflect any significant structural or functional features of activa- tion domains. The VP16 activation domain, considered to be the prototype for the acidic class of activators, has been reported to interact with TBP (Stringer et al., 1990) and TFIIB (Lin et al., 1991) by in vitro binding assays, although the importance of these interactions in assembly an activated transcription complex remains unclear. Thus far, no potential targets for proline or glutamine-rich activation domains have been identified by direct binding studies. Human transcription factor Spl contains two glutamine- rich activation domains that can function as potent activa- tors (Courey and Tjian, 1988). We have used Spl as a prototype activator for investigating the mechanisms of regulation by eukaryotic transcription factors. In addition, recent studies reveal that these glutamine-rich activation domains of Spl also function as Protein-Protein interac- tion surfaces for the formation of homomultimers (Pascal and Tjian, 1991) as well as interfaces for interactions with the basal machinery. In this report, we describe a specific component of the
Timothy Hoey - One of the best experts on this subject based on the ideXlab platform.
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molecular cloning and functional analysis of drosophila TAF110 reveal properties expected of coactivators
Cell, 1993Co-Authors: Timothy Hoey, Robert O J Weinzierl, Grace Gill, Jinlong Chen, Brian David Dynlacht, Robert TjianAbstract:The general transcription factor TFIID is a multiProtein complex containing the TATA-binding Protein and several associated factors (TAFs), some of which may function as coactivators that are essential for activated, but not basal, transcription. Here we describe the isolation and characterization of the first gene encoding a TAF Protein. The deduced amino acid sequence of TAF110 revealed the presence of several glutamine- and serine/threonine-rich regions reminiscent of the Protein-Protein interaction domains of the regulatory transcription factor Sp1 that are involved in transcription activation and multimerization. In both Drosophila cells and yeast, TAF110 specifically interacts with the glutamine-rich activation domains of Sp1. Moreover, purified Sp1 selectively binds recombinant TAF110 in vitro. These findings taken together suggest that TAF110 may function as a coactivator by serving as a site of Protein-Protein contact between activators like Sp1 and the TFIID complex.
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lkdecular Cloning and Functionai Anatysis of0 ila TAFI 10 Rev& Expec4ed of Coactiiators
1993Co-Authors: Timothy Hoey, Grace Gill, Jinlong Chen, Brian David Dynlacht, J. Weinzierl, Robert TjianAbstract:Timothy Hoey, Robert 0. J. Weinzierl, Grace Gill, Jin-Long Chen, Brian David Dynlacht, and Robert Tjian Howard Hughes Medical Institute Department of Molecular and Cell Biology University of California at Berkeley Berkeley, California 94720 Summary The general transcription factor TFIID is a multiProtein complex containing the TATA-binding Protein and sev- eral associated factors (TAFs), some of which may function as coactivators that are essential for acti- vated, but not basal, transcription. Here we describe the isolation and characterization of the first gene en- coding a TAF Protein. The deduced amino acid se- quence of TAFllO revealed the presence of several glutamine- and serinelthreonine-rich regions reminis- cent of the Protein-Protein interaction domains of the regulatory transcription factor Spl that are involved in transcription activation and multimerization. In both Drosophila cells and yeast, TAFl 10 specifically inter- acts with the glutamincrich activation domains of Spl . Moreover, purified Spl selectively binds recombinant TAFllO in vitro. These findings taken together sug- gest that TAFllO may function as a coactivator by serving as a site of Protein-Protein contact between activators like Spl and the TFIID complex. Introduction How do sequence-specific DNA binding factors communi- cate with the transcriptional machinery to regulate rates of transcriptional initiation? A model that has gained increas- ing acceptance proposes that site-specific transcriptional activators and repressors interact directly with one or more of the accessory Proteins that form the initiation complex assembled at the promoter (for reviews see Gill and Tjian, 1992; Roeder, 1991). It is, at present, unknown whether ail RNA polymerase II regulatory factors work via a common mechanism during the assembly of an active initiation complex or whether different transcriptional activators function by interacting with different target Proteins in the initiation complex. To study the mechanisms involved in transcriptional control, the specific components required to assemble an activated transcriptional complex must first be biochemically defined. In recent years, aconcerted effort has been devoted to the purification, characteriza- tion, and subsequent molecular cloning of the genes en- coding all of the components of the transcription machin- ery for RNA poiymerase Ii (TFIIA, B, D, E, F, and H; for review see Zawei and Reinberg, 1992). These studies have, in some instances, revealed unexpected results that have profoundly altered our view of how activation of tran- scription occurs. For example, the cloning of the TATA- binding Protein (TBP) gene led to the finding that TFIID is not a single Protein, as had been generally assumed. Instead, in higher eukaryotes, TFIID consists of a multisub- unit complex containing the TBP and at least seven distinct and tightly associated factors, called TAFs (Dynlacht et al., 1991; Tanese et 1991). An important property of TAFs is that they are essential for mediating regulated transcription but are not required for basal activity. Thus, TAFs have the biochemical activi- ties expected of coactivators (Dynlacht et al., 1991; Tanese et al., 1991). It is not known how TAFs or coactiva- tors function to mediate regulated transcription, nor is it known whether ail TAFs serve as coactivators. In the sim- plest model, we originally proposed that coactivator pro- teins could serve as adaptor molecules connecting the activation domains of regulatory factors and the basal tran- scriptional machinery (Pugh and Tjian, 1990), and we speculated that perhaps different classes of activators have different coactivator requirements. Studies in yeast have identified an activity, termed a mediator or adaptor, that may function as a bridging Protein between the tran- scriptional activator VP16 and the basal factors there- fore may be similar to coactivators (Berger et al., 1990; Kelleher et al., 1990; Flanagan et al., 1991). Unlike TAFs, the adaptor or mediator Proteins in yeast do not appear to be stably associated with TBP, which can be purified from yeast as a free Protein (Buratowski et al., 1988). Eukaryotic transcription factors have a modular design with separable DNA-binding and activation domains (for review see Frankel and Kim, 1991). Transcriptional activa- tion domains can be thought of as those parts of regulatory factors that are specialized for Protein-Protein interaction with some component of the transcription initiation com- plex. Transcriptional activation domains are typically di- vided into three major classes based on their amino acid sequences: those rich in acidic, glutamine, or proline resi- dues (for review see Mitchell and Tjian, 1989). It is, at present, unknown whether these classifications reflect any significant structural or functional features of activa- tion domains. The VP16 activation domain, considered to be the prototype for the acidic class of activators, has been reported to interact with TBP (Stringer et al., 1990) and TFIIB (Lin et al., 1991) by in vitro binding assays, although the importance of these interactions in assembly an activated transcription complex remains unclear. Thus far, no potential targets for proline or glutamine-rich activation domains have been identified by direct binding studies. Human transcription factor Spl contains two glutamine- rich activation domains that can function as potent activa- tors (Courey and Tjian, 1988). We have used Spl as a prototype activator for investigating the mechanisms of regulation by eukaryotic transcription factors. In addition, recent studies reveal that these glutamine-rich activation domains of Spl also function as Protein-Protein interac- tion surfaces for the formation of homomultimers (Pascal and Tjian, 1991) as well as interfaces for interactions with the basal machinery. In this report, we describe a specific component of the
Brian David Dynlacht - One of the best experts on this subject based on the ideXlab platform.
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molecular cloning and functional analysis of drosophila TAF110 reveal properties expected of coactivators
Cell, 1993Co-Authors: Timothy Hoey, Robert O J Weinzierl, Grace Gill, Jinlong Chen, Brian David Dynlacht, Robert TjianAbstract:The general transcription factor TFIID is a multiProtein complex containing the TATA-binding Protein and several associated factors (TAFs), some of which may function as coactivators that are essential for activated, but not basal, transcription. Here we describe the isolation and characterization of the first gene encoding a TAF Protein. The deduced amino acid sequence of TAF110 revealed the presence of several glutamine- and serine/threonine-rich regions reminiscent of the Protein-Protein interaction domains of the regulatory transcription factor Sp1 that are involved in transcription activation and multimerization. In both Drosophila cells and yeast, TAF110 specifically interacts with the glutamine-rich activation domains of Sp1. Moreover, purified Sp1 selectively binds recombinant TAF110 in vitro. These findings taken together suggest that TAF110 may function as a coactivator by serving as a site of Protein-Protein contact between activators like Sp1 and the TFIID complex.
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lkdecular Cloning and Functionai Anatysis of0 ila TAFI 10 Rev& Expec4ed of Coactiiators
1993Co-Authors: Timothy Hoey, Grace Gill, Jinlong Chen, Brian David Dynlacht, J. Weinzierl, Robert TjianAbstract:Timothy Hoey, Robert 0. J. Weinzierl, Grace Gill, Jin-Long Chen, Brian David Dynlacht, and Robert Tjian Howard Hughes Medical Institute Department of Molecular and Cell Biology University of California at Berkeley Berkeley, California 94720 Summary The general transcription factor TFIID is a multiProtein complex containing the TATA-binding Protein and sev- eral associated factors (TAFs), some of which may function as coactivators that are essential for acti- vated, but not basal, transcription. Here we describe the isolation and characterization of the first gene en- coding a TAF Protein. The deduced amino acid se- quence of TAFllO revealed the presence of several glutamine- and serinelthreonine-rich regions reminis- cent of the Protein-Protein interaction domains of the regulatory transcription factor Spl that are involved in transcription activation and multimerization. In both Drosophila cells and yeast, TAFl 10 specifically inter- acts with the glutamincrich activation domains of Spl . Moreover, purified Spl selectively binds recombinant TAFllO in vitro. These findings taken together sug- gest that TAFllO may function as a coactivator by serving as a site of Protein-Protein contact between activators like Spl and the TFIID complex. Introduction How do sequence-specific DNA binding factors communi- cate with the transcriptional machinery to regulate rates of transcriptional initiation? A model that has gained increas- ing acceptance proposes that site-specific transcriptional activators and repressors interact directly with one or more of the accessory Proteins that form the initiation complex assembled at the promoter (for reviews see Gill and Tjian, 1992; Roeder, 1991). It is, at present, unknown whether ail RNA polymerase II regulatory factors work via a common mechanism during the assembly of an active initiation complex or whether different transcriptional activators function by interacting with different target Proteins in the initiation complex. To study the mechanisms involved in transcriptional control, the specific components required to assemble an activated transcriptional complex must first be biochemically defined. In recent years, aconcerted effort has been devoted to the purification, characteriza- tion, and subsequent molecular cloning of the genes en- coding all of the components of the transcription machin- ery for RNA poiymerase Ii (TFIIA, B, D, E, F, and H; for review see Zawei and Reinberg, 1992). These studies have, in some instances, revealed unexpected results that have profoundly altered our view of how activation of tran- scription occurs. For example, the cloning of the TATA- binding Protein (TBP) gene led to the finding that TFIID is not a single Protein, as had been generally assumed. Instead, in higher eukaryotes, TFIID consists of a multisub- unit complex containing the TBP and at least seven distinct and tightly associated factors, called TAFs (Dynlacht et al., 1991; Tanese et 1991). An important property of TAFs is that they are essential for mediating regulated transcription but are not required for basal activity. Thus, TAFs have the biochemical activi- ties expected of coactivators (Dynlacht et al., 1991; Tanese et al., 1991). It is not known how TAFs or coactiva- tors function to mediate regulated transcription, nor is it known whether ail TAFs serve as coactivators. In the sim- plest model, we originally proposed that coactivator pro- teins could serve as adaptor molecules connecting the activation domains of regulatory factors and the basal tran- scriptional machinery (Pugh and Tjian, 1990), and we speculated that perhaps different classes of activators have different coactivator requirements. Studies in yeast have identified an activity, termed a mediator or adaptor, that may function as a bridging Protein between the tran- scriptional activator VP16 and the basal factors there- fore may be similar to coactivators (Berger et al., 1990; Kelleher et al., 1990; Flanagan et al., 1991). Unlike TAFs, the adaptor or mediator Proteins in yeast do not appear to be stably associated with TBP, which can be purified from yeast as a free Protein (Buratowski et al., 1988). Eukaryotic transcription factors have a modular design with separable DNA-binding and activation domains (for review see Frankel and Kim, 1991). Transcriptional activa- tion domains can be thought of as those parts of regulatory factors that are specialized for Protein-Protein interaction with some component of the transcription initiation com- plex. Transcriptional activation domains are typically di- vided into three major classes based on their amino acid sequences: those rich in acidic, glutamine, or proline resi- dues (for review see Mitchell and Tjian, 1989). It is, at present, unknown whether these classifications reflect any significant structural or functional features of activa- tion domains. The VP16 activation domain, considered to be the prototype for the acidic class of activators, has been reported to interact with TBP (Stringer et al., 1990) and TFIIB (Lin et al., 1991) by in vitro binding assays, although the importance of these interactions in assembly an activated transcription complex remains unclear. Thus far, no potential targets for proline or glutamine-rich activation domains have been identified by direct binding studies. Human transcription factor Spl contains two glutamine- rich activation domains that can function as potent activa- tors (Courey and Tjian, 1988). We have used Spl as a prototype activator for investigating the mechanisms of regulation by eukaryotic transcription factors. In addition, recent studies reveal that these glutamine-rich activation domains of Spl also function as Protein-Protein interac- tion surfaces for the formation of homomultimers (Pascal and Tjian, 1991) as well as interfaces for interactions with the basal machinery. In this report, we describe a specific component of the
Jinlong Chen - One of the best experts on this subject based on the ideXlab platform.
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molecular cloning and functional analysis of drosophila TAF110 reveal properties expected of coactivators
Cell, 1993Co-Authors: Timothy Hoey, Robert O J Weinzierl, Grace Gill, Jinlong Chen, Brian David Dynlacht, Robert TjianAbstract:The general transcription factor TFIID is a multiProtein complex containing the TATA-binding Protein and several associated factors (TAFs), some of which may function as coactivators that are essential for activated, but not basal, transcription. Here we describe the isolation and characterization of the first gene encoding a TAF Protein. The deduced amino acid sequence of TAF110 revealed the presence of several glutamine- and serine/threonine-rich regions reminiscent of the Protein-Protein interaction domains of the regulatory transcription factor Sp1 that are involved in transcription activation and multimerization. In both Drosophila cells and yeast, TAF110 specifically interacts with the glutamine-rich activation domains of Sp1. Moreover, purified Sp1 selectively binds recombinant TAF110 in vitro. These findings taken together suggest that TAF110 may function as a coactivator by serving as a site of Protein-Protein contact between activators like Sp1 and the TFIID complex.
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lkdecular Cloning and Functionai Anatysis of0 ila TAFI 10 Rev& Expec4ed of Coactiiators
1993Co-Authors: Timothy Hoey, Grace Gill, Jinlong Chen, Brian David Dynlacht, J. Weinzierl, Robert TjianAbstract:Timothy Hoey, Robert 0. J. Weinzierl, Grace Gill, Jin-Long Chen, Brian David Dynlacht, and Robert Tjian Howard Hughes Medical Institute Department of Molecular and Cell Biology University of California at Berkeley Berkeley, California 94720 Summary The general transcription factor TFIID is a multiProtein complex containing the TATA-binding Protein and sev- eral associated factors (TAFs), some of which may function as coactivators that are essential for acti- vated, but not basal, transcription. Here we describe the isolation and characterization of the first gene en- coding a TAF Protein. The deduced amino acid se- quence of TAFllO revealed the presence of several glutamine- and serinelthreonine-rich regions reminis- cent of the Protein-Protein interaction domains of the regulatory transcription factor Spl that are involved in transcription activation and multimerization. In both Drosophila cells and yeast, TAFl 10 specifically inter- acts with the glutamincrich activation domains of Spl . Moreover, purified Spl selectively binds recombinant TAFllO in vitro. These findings taken together sug- gest that TAFllO may function as a coactivator by serving as a site of Protein-Protein contact between activators like Spl and the TFIID complex. Introduction How do sequence-specific DNA binding factors communi- cate with the transcriptional machinery to regulate rates of transcriptional initiation? A model that has gained increas- ing acceptance proposes that site-specific transcriptional activators and repressors interact directly with one or more of the accessory Proteins that form the initiation complex assembled at the promoter (for reviews see Gill and Tjian, 1992; Roeder, 1991). It is, at present, unknown whether ail RNA polymerase II regulatory factors work via a common mechanism during the assembly of an active initiation complex or whether different transcriptional activators function by interacting with different target Proteins in the initiation complex. To study the mechanisms involved in transcriptional control, the specific components required to assemble an activated transcriptional complex must first be biochemically defined. In recent years, aconcerted effort has been devoted to the purification, characteriza- tion, and subsequent molecular cloning of the genes en- coding all of the components of the transcription machin- ery for RNA poiymerase Ii (TFIIA, B, D, E, F, and H; for review see Zawei and Reinberg, 1992). These studies have, in some instances, revealed unexpected results that have profoundly altered our view of how activation of tran- scription occurs. For example, the cloning of the TATA- binding Protein (TBP) gene led to the finding that TFIID is not a single Protein, as had been generally assumed. Instead, in higher eukaryotes, TFIID consists of a multisub- unit complex containing the TBP and at least seven distinct and tightly associated factors, called TAFs (Dynlacht et al., 1991; Tanese et 1991). An important property of TAFs is that they are essential for mediating regulated transcription but are not required for basal activity. Thus, TAFs have the biochemical activi- ties expected of coactivators (Dynlacht et al., 1991; Tanese et al., 1991). It is not known how TAFs or coactiva- tors function to mediate regulated transcription, nor is it known whether ail TAFs serve as coactivators. In the sim- plest model, we originally proposed that coactivator pro- teins could serve as adaptor molecules connecting the activation domains of regulatory factors and the basal tran- scriptional machinery (Pugh and Tjian, 1990), and we speculated that perhaps different classes of activators have different coactivator requirements. Studies in yeast have identified an activity, termed a mediator or adaptor, that may function as a bridging Protein between the tran- scriptional activator VP16 and the basal factors there- fore may be similar to coactivators (Berger et al., 1990; Kelleher et al., 1990; Flanagan et al., 1991). Unlike TAFs, the adaptor or mediator Proteins in yeast do not appear to be stably associated with TBP, which can be purified from yeast as a free Protein (Buratowski et al., 1988). Eukaryotic transcription factors have a modular design with separable DNA-binding and activation domains (for review see Frankel and Kim, 1991). Transcriptional activa- tion domains can be thought of as those parts of regulatory factors that are specialized for Protein-Protein interaction with some component of the transcription initiation com- plex. Transcriptional activation domains are typically di- vided into three major classes based on their amino acid sequences: those rich in acidic, glutamine, or proline resi- dues (for review see Mitchell and Tjian, 1989). It is, at present, unknown whether these classifications reflect any significant structural or functional features of activa- tion domains. The VP16 activation domain, considered to be the prototype for the acidic class of activators, has been reported to interact with TBP (Stringer et al., 1990) and TFIIB (Lin et al., 1991) by in vitro binding assays, although the importance of these interactions in assembly an activated transcription complex remains unclear. Thus far, no potential targets for proline or glutamine-rich activation domains have been identified by direct binding studies. Human transcription factor Spl contains two glutamine- rich activation domains that can function as potent activa- tors (Courey and Tjian, 1988). We have used Spl as a prototype activator for investigating the mechanisms of regulation by eukaryotic transcription factors. In addition, recent studies reveal that these glutamine-rich activation domains of Spl also function as Protein-Protein interac- tion surfaces for the formation of homomultimers (Pascal and Tjian, 1991) as well as interfaces for interactions with the basal machinery. In this report, we describe a specific component of the
Grace Gill - One of the best experts on this subject based on the ideXlab platform.
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molecular cloning and functional analysis of drosophila TAF110 reveal properties expected of coactivators
Cell, 1993Co-Authors: Timothy Hoey, Robert O J Weinzierl, Grace Gill, Jinlong Chen, Brian David Dynlacht, Robert TjianAbstract:The general transcription factor TFIID is a multiProtein complex containing the TATA-binding Protein and several associated factors (TAFs), some of which may function as coactivators that are essential for activated, but not basal, transcription. Here we describe the isolation and characterization of the first gene encoding a TAF Protein. The deduced amino acid sequence of TAF110 revealed the presence of several glutamine- and serine/threonine-rich regions reminiscent of the Protein-Protein interaction domains of the regulatory transcription factor Sp1 that are involved in transcription activation and multimerization. In both Drosophila cells and yeast, TAF110 specifically interacts with the glutamine-rich activation domains of Sp1. Moreover, purified Sp1 selectively binds recombinant TAF110 in vitro. These findings taken together suggest that TAF110 may function as a coactivator by serving as a site of Protein-Protein contact between activators like Sp1 and the TFIID complex.
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lkdecular Cloning and Functionai Anatysis of0 ila TAFI 10 Rev& Expec4ed of Coactiiators
1993Co-Authors: Timothy Hoey, Grace Gill, Jinlong Chen, Brian David Dynlacht, J. Weinzierl, Robert TjianAbstract:Timothy Hoey, Robert 0. J. Weinzierl, Grace Gill, Jin-Long Chen, Brian David Dynlacht, and Robert Tjian Howard Hughes Medical Institute Department of Molecular and Cell Biology University of California at Berkeley Berkeley, California 94720 Summary The general transcription factor TFIID is a multiProtein complex containing the TATA-binding Protein and sev- eral associated factors (TAFs), some of which may function as coactivators that are essential for acti- vated, but not basal, transcription. Here we describe the isolation and characterization of the first gene en- coding a TAF Protein. The deduced amino acid se- quence of TAFllO revealed the presence of several glutamine- and serinelthreonine-rich regions reminis- cent of the Protein-Protein interaction domains of the regulatory transcription factor Spl that are involved in transcription activation and multimerization. In both Drosophila cells and yeast, TAFl 10 specifically inter- acts with the glutamincrich activation domains of Spl . Moreover, purified Spl selectively binds recombinant TAFllO in vitro. These findings taken together sug- gest that TAFllO may function as a coactivator by serving as a site of Protein-Protein contact between activators like Spl and the TFIID complex. Introduction How do sequence-specific DNA binding factors communi- cate with the transcriptional machinery to regulate rates of transcriptional initiation? A model that has gained increas- ing acceptance proposes that site-specific transcriptional activators and repressors interact directly with one or more of the accessory Proteins that form the initiation complex assembled at the promoter (for reviews see Gill and Tjian, 1992; Roeder, 1991). It is, at present, unknown whether ail RNA polymerase II regulatory factors work via a common mechanism during the assembly of an active initiation complex or whether different transcriptional activators function by interacting with different target Proteins in the initiation complex. To study the mechanisms involved in transcriptional control, the specific components required to assemble an activated transcriptional complex must first be biochemically defined. In recent years, aconcerted effort has been devoted to the purification, characteriza- tion, and subsequent molecular cloning of the genes en- coding all of the components of the transcription machin- ery for RNA poiymerase Ii (TFIIA, B, D, E, F, and H; for review see Zawei and Reinberg, 1992). These studies have, in some instances, revealed unexpected results that have profoundly altered our view of how activation of tran- scription occurs. For example, the cloning of the TATA- binding Protein (TBP) gene led to the finding that TFIID is not a single Protein, as had been generally assumed. Instead, in higher eukaryotes, TFIID consists of a multisub- unit complex containing the TBP and at least seven distinct and tightly associated factors, called TAFs (Dynlacht et al., 1991; Tanese et 1991). An important property of TAFs is that they are essential for mediating regulated transcription but are not required for basal activity. Thus, TAFs have the biochemical activi- ties expected of coactivators (Dynlacht et al., 1991; Tanese et al., 1991). It is not known how TAFs or coactiva- tors function to mediate regulated transcription, nor is it known whether ail TAFs serve as coactivators. In the sim- plest model, we originally proposed that coactivator pro- teins could serve as adaptor molecules connecting the activation domains of regulatory factors and the basal tran- scriptional machinery (Pugh and Tjian, 1990), and we speculated that perhaps different classes of activators have different coactivator requirements. Studies in yeast have identified an activity, termed a mediator or adaptor, that may function as a bridging Protein between the tran- scriptional activator VP16 and the basal factors there- fore may be similar to coactivators (Berger et al., 1990; Kelleher et al., 1990; Flanagan et al., 1991). Unlike TAFs, the adaptor or mediator Proteins in yeast do not appear to be stably associated with TBP, which can be purified from yeast as a free Protein (Buratowski et al., 1988). Eukaryotic transcription factors have a modular design with separable DNA-binding and activation domains (for review see Frankel and Kim, 1991). Transcriptional activa- tion domains can be thought of as those parts of regulatory factors that are specialized for Protein-Protein interaction with some component of the transcription initiation com- plex. Transcriptional activation domains are typically di- vided into three major classes based on their amino acid sequences: those rich in acidic, glutamine, or proline resi- dues (for review see Mitchell and Tjian, 1989). It is, at present, unknown whether these classifications reflect any significant structural or functional features of activa- tion domains. The VP16 activation domain, considered to be the prototype for the acidic class of activators, has been reported to interact with TBP (Stringer et al., 1990) and TFIIB (Lin et al., 1991) by in vitro binding assays, although the importance of these interactions in assembly an activated transcription complex remains unclear. Thus far, no potential targets for proline or glutamine-rich activation domains have been identified by direct binding studies. Human transcription factor Spl contains two glutamine- rich activation domains that can function as potent activa- tors (Courey and Tjian, 1988). We have used Spl as a prototype activator for investigating the mechanisms of regulation by eukaryotic transcription factors. In addition, recent studies reveal that these glutamine-rich activation domains of Spl also function as Protein-Protein interac- tion surfaces for the formation of homomultimers (Pascal and Tjian, 1991) as well as interfaces for interactions with the basal machinery. In this report, we describe a specific component of the
