The Experts below are selected from a list of 243 Experts worldwide ranked by ideXlab platform
Antonio Puyet - One of the best experts on this subject based on the ideXlab platform.
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The Maltose / Maltodextrin Regulon of Streptococcus pneumoniae
The Journal of Biological Chemistry, 1997Co-Authors: Concepcion Nieto, Manuel Espinosa, Antonio PuyetAbstract:The Streptococcus pneumoniae MalR protein regu- lates the transcription of two divergent operons, malXCD and malMP, involved in maltosaccharide up- take and utilization, respectively. MalR belongs to the LacI-GalR family of transcription Repressors. The pro- tein binds specifically to two operator sequences in the intergenic region between these operons. The affinity of MalR for the malMP binding sequence is higher than for the malXCD site. Results obtained in vivo using tran- scriptional fusions with reporter genes indicate low re- pression level of malXCD by MalR when compared with malMP. This behavior may be correlated with the exist- ence of separate induction pathways for maltose, malto- triose, and maltotetraose. The similarities found at the operator sequences and binding domains for MalR and enterococcal Repressor Proteins suggest that the pneu- mococcal maltosaccharide regulation system is closely related to several Gram-negative metabolic pathways, but not to the structurally similar Escherichia coli malt- ose regulon. Bacterial
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The maltose/maltodextrin regulon of Streptococcus pneumoniae
J. Biol. Chem., 1997Co-Authors: Concepcion Nieto, Manuel Espinosa, Antonio PuyetAbstract:The Streptococcus pneumoniae MalR protein regulates the transcription of two divergent operons,malXCD and malMP, involved in maltosaccharide uptake and utilization, respectively. MalR belongs to the LacI-GalR family of transcription Repressors. The protein binds specifically to two operator sequences in the intergenic region between these operons. The affinity of MalR for the malMP binding sequence is higher than for the malXCD site. Results obtained in vivo using transcriptional fusions with reporter genes indicate low repression level of malXCD by MalR when compared withmalMP. This behavior may be correlated with the existence of separate induction pathways for maltose, maltotriose, and maltotetraose. The similarities found at the operator sequences and binding domains for MalR and enterococcal Repressor Proteins suggest that the pneumococcal maltosaccharide regulation system is closely related to several Gram-negative metabolic pathways, but not to the structurally similar Escherichia coli maltose regulon.
Mario H Skiadopoulos - One of the best experts on this subject based on the ideXlab platform.
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bovine papillomavirus type 1 genomes and the e2 transactivator protein are closely associated with mitotic chromatin
Journal of Virology, 1998Co-Authors: Mario H Skiadopoulos, Alison A McbrideAbstract:The bovine papillomavirus type 1 E2 transactivator protein is required for viral transcriptional regulation and DNA replication and may be important for long-term episomal maintenance of viral genomes within replicating cells (M. Piirsoo, E. Ustav, T. Mandel, A. Stenlund, and M. Ustav, EMBO J. 15:1–11, 1996). We have evidence that, in contrast to most other transcriptional transactivators, the E2 transactivator protein is associated with mitotic chromosomes in dividing cells. The shorter E2-TR and E8/E2 Repressor Proteins do not bind to mitotic chromatin, and the N-terminal transactivation domain of the E2 protein is necessary for the association. However, the DNA binding function of E2 is not required. We have found that bovine papillomavirus type 1 genomes are also associated with mitotic chromosomes, and we propose a model in which E2-bound viral genomes are transiently associated with cellular chromosomes during mitosis to ensure that viral genomes are segregated to daughter cells in approximately equal numbers.
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the bovine papillomavirus type 1 e2 transactivator and Repressor Proteins use different nuclear localization signals
Journal of Virology, 1996Co-Authors: Mario H Skiadopoulos, Andalison A McbrideAbstract:The E2 gene of bovine papillomavirus type 1 encodes at least three nuclear phosphoProteins that regulate viral transcription and DNA replication. All three Proteins have a common C-terminal domain that has DNA-binding and dimerization activities. A basic region in this domain forms an alpha helix which makes direct contact with the DNA target. In this study, it is shown that in addition to its role in DNA binding, this basic region functions as a nuclear localization signal both in the E2 DNA-binding domain and in a heterologous protein. Deletion of this signal sequence resulted in increased accumulation of the E2 transactivator and Repressor Proteins in the cytoplasm, but nuclear localization was not eliminated. In the full-length transactivator protein, another signal, present in the N-terminal transactivation domain, is used for transport to the nucleus, and the C-terminal nuclear localization signal(s) are masked. The use of different nuclear localization signals could potentially allow differential regulation of the subcellular localization of the E2 transactivator and Repressor Proteins at some stage in the viral life cycle.
Michael Caudy - One of the best experts on this subject based on the ideXlab platform.
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the function of hairy related bhlh Repressor Proteins in cell fate decisions
BioEssays, 1998Co-Authors: Alfred L Fisher, Michael CaudyAbstract:Hairy-related Proteins are a distinct subfamily of basic helix-loop-helix (bHLH) Proteins that generally function as DNA-binding transcriptional Repressors. These Proteins act in opposition to bHLH transcriptional activator Proteins such as the proneural and myogenic Proteins; together, the activator and Repressor genes that encode these Proteins have co-evolved as a regulatory gene “cassette” or “module” for controlling cell fate decisions. In the development of the Drosophila peripheral nervous system, Hairy-related genes function at multiple steps during neurogenesis, for example, as positional information genes that establish the “prepattern” that controls where “proneural cluster” equivalence groups will form, and later as nuclear effectors of the Notch signaling pathway to “single out” individual precursor cells within the equivalence group. Hairy-related genes also function in the establishment and restriction of other types of equivalence groups, such as those for muscle and Malphigian tubule precursors. This general function in cell fate specification has been conserved from Drosophila to vertebrates and has implications for human disease pathogenesis. BioEssays20:298-306, 1998.© 1998 John Wiley & Sons, Inc.
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the wrpw motif of the hairy related basic helix loop helix Repressor Proteins acts as a 4 amino acid transcription repression and protein protein interaction domain
Molecular and Cellular Biology, 1996Co-Authors: Alfred L Fisher, Shunji Ohsako, Michael CaudyAbstract:Hairy-related Proteins include the Drosophila Hairy and Enhancer of Split Proteins and mammalian Hes Proteins. These Proteins are basic helix-loop-helix (bHLH) transcriptional Repressors that control cell fate decisions such as neurogenesis or myogenesis in both Drosophila melanogaster and mammals. Hairy-related Proteins are site-specific DNA-binding Proteins defined by the presence of both a Repressor-specific bHLH DNA binding domain and a carboxyl-terminal WRPW (Trp-Arg-Pro-Trp) motif. These Proteins act as Repressors by binding to DNA sites in target gene promoters and not by interfering with activator Proteins, indicating that these Proteins are active Repressors which should therefore have specific repression domains. Here we show the WRPW motif to be a functional transcriptional repression domain sufficient to confer active repression to Hairy-related Proteins or a heterologous DNA-binding protein, Ga14. This motif was previously shown to be necessary for interactions with Groucho, a genetically defined coRepressor for Drosophila Hairy-related Proteins. Here we show that the WRPW motif is sufficient to recruit Groucho or the TLE mammalian homologs to target gene promoters. We also show that Groucho and TLE Proteins actively repress transcription when directly bound to a target gene promoter and identify a novel, highly conserved transcriptional repression domain in these Proteins. These results directly demonstrate that Groucho family Proteins are active transcriptional coRepressors for Hairy-related Proteins and are recruited by the 4-amino acid protein-protein interaction domain, WRPW.
Concepcion Nieto - One of the best experts on this subject based on the ideXlab platform.
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The Maltose / Maltodextrin Regulon of Streptococcus pneumoniae
The Journal of Biological Chemistry, 1997Co-Authors: Concepcion Nieto, Manuel Espinosa, Antonio PuyetAbstract:The Streptococcus pneumoniae MalR protein regu- lates the transcription of two divergent operons, malXCD and malMP, involved in maltosaccharide up- take and utilization, respectively. MalR belongs to the LacI-GalR family of transcription Repressors. The pro- tein binds specifically to two operator sequences in the intergenic region between these operons. The affinity of MalR for the malMP binding sequence is higher than for the malXCD site. Results obtained in vivo using tran- scriptional fusions with reporter genes indicate low re- pression level of malXCD by MalR when compared with malMP. This behavior may be correlated with the exist- ence of separate induction pathways for maltose, malto- triose, and maltotetraose. The similarities found at the operator sequences and binding domains for MalR and enterococcal Repressor Proteins suggest that the pneu- mococcal maltosaccharide regulation system is closely related to several Gram-negative metabolic pathways, but not to the structurally similar Escherichia coli malt- ose regulon. Bacterial
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The maltose/maltodextrin regulon of Streptococcus pneumoniae
J. Biol. Chem., 1997Co-Authors: Concepcion Nieto, Manuel Espinosa, Antonio PuyetAbstract:The Streptococcus pneumoniae MalR protein regulates the transcription of two divergent operons,malXCD and malMP, involved in maltosaccharide uptake and utilization, respectively. MalR belongs to the LacI-GalR family of transcription Repressors. The protein binds specifically to two operator sequences in the intergenic region between these operons. The affinity of MalR for the malMP binding sequence is higher than for the malXCD site. Results obtained in vivo using transcriptional fusions with reporter genes indicate low repression level of malXCD by MalR when compared withmalMP. This behavior may be correlated with the existence of separate induction pathways for maltose, maltotriose, and maltotetraose. The similarities found at the operator sequences and binding domains for MalR and enterococcal Repressor Proteins suggest that the pneumococcal maltosaccharide regulation system is closely related to several Gram-negative metabolic pathways, but not to the structurally similar Escherichia coli maltose regulon.
Alison A Mcbride - One of the best experts on this subject based on the ideXlab platform.
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bovine papillomavirus type 1 genomes and the e2 transactivator protein are closely associated with mitotic chromatin
Journal of Virology, 1998Co-Authors: Mario H Skiadopoulos, Alison A McbrideAbstract:The bovine papillomavirus type 1 E2 transactivator protein is required for viral transcriptional regulation and DNA replication and may be important for long-term episomal maintenance of viral genomes within replicating cells (M. Piirsoo, E. Ustav, T. Mandel, A. Stenlund, and M. Ustav, EMBO J. 15:1–11, 1996). We have evidence that, in contrast to most other transcriptional transactivators, the E2 transactivator protein is associated with mitotic chromosomes in dividing cells. The shorter E2-TR and E8/E2 Repressor Proteins do not bind to mitotic chromatin, and the N-terminal transactivation domain of the E2 protein is necessary for the association. However, the DNA binding function of E2 is not required. We have found that bovine papillomavirus type 1 genomes are also associated with mitotic chromosomes, and we propose a model in which E2-bound viral genomes are transiently associated with cellular chromosomes during mitosis to ensure that viral genomes are segregated to daughter cells in approximately equal numbers.