The Experts below are selected from a list of 2292 Experts worldwide ranked by ideXlab platform
Cheng Ming Chiang - One of the best experts on this subject based on the ideXlab platform.
-
the general transcription machinery and general cofactors
Critical Reviews in Biochemistry and Molecular Biology, 2006Co-Authors: Mary C Thomas, Cheng Ming ChiangAbstract:ABSTRACTIn eukaryotes, the core promoter serves as a platform for the assembly of transcription preinitiation complex (PIC) that includes TFIIA, TFIIB, TFIID, TFIIE, TFIIF, TFIIH, and RNA polymerase II (pol II), which function collectively to specify the transcription start site. PIC formation usually begins with TFIID binding to the TATA box, initiator, and/or downstream promoter element (DPE) found in most core promoters, followed by the entry of other general transcription factors (GTFs) and pol II through either a sequential assembly or a preassembled pol II holoenzyme pathway. Formation of this promoter-bound complex is sufficient for a basal level of transcription. However, for activator-dependent (or regulated) transcription, general cofactors are often required to transmit regulatory signals between gene-specific activators and the general transcription machinery. Three classes of general cofactors, including TBP-associated factors (TAFs), Mediator, and upstream stimulatory activity (USA)-derived ...
-
The general transcription machinery and general cofactors.
Critical Reviews in Biochemistry and Molecular Biology, 2006Co-Authors: Mary C Thomas, Cheng Ming ChiangAbstract:ABSTRACTIn eukaryotes, the core promoter serves as a platform for the assembly of transcription preinitiation complex (PIC) that includes TFIIA, TFIIB, TFIID, TFIIE, TFIIF, TFIIH, and RNA polymerase II (pol II), which function collectively to specify the transcription start site. PIC formation usually begins with TFIID binding to the TATA box, initiator, and/or downstream promoter element (DPE) found in most core promoters, followed by the entry of other general transcription factors (GTFs) and pol II through either a sequential assembly or a preassembled pol II holoenzyme pathway. Formation of this promoter-bound complex is sufficient for a basal level of transcription. However, for activator-dependent (or regulated) transcription, general cofactors are often required to transmit regulatory signals between gene-specific activators and the general transcription machinery. Three classes of general cofactors, including TBP-associated factors (TAFs), Mediator, and upstream stimulatory activity (USA)-derived ...
Carol A. Fierke - One of the best experts on this subject based on the ideXlab platform.
-
General Base–General Acid Catalysis in Human Histone Deacetylase 8
Biochemistry, 2016Co-Authors: M. Lucy Gantt, David W. Christianson, Christophe Decroos, Matthew Lee, Laura E. Gullett, Christine M. Bowman, Carol A. FierkeAbstract:Histone deacetylases (HDACs) regulate cellular processes such as differentiation and apoptosis and are targeted by anticancer therapeutics in development and in the clinic. HDAC8 is a metal-dependent class I HDAC and is proposed to use a general acid–base catalytic pair in the mechanism of amide bond hydrolysis. Here, we report site-directed mutagenesis and enzymological measurements to elucidate the catalytic mechanism of HDAC8. Specifically, we focus on the catalytic function of Y306 and the histidine-aspartate dyads H142-D176 and H143-D183. Additionally, we report X-ray crystal structures of four representative HDAC8 mutants: D176N, D176N/Y306F, D176A/Y306F, and H142A/Y306F. These structures provide a useful framework for understanding enzymological measurements. The pH dependence of kcat/KM for wild-type Co(II)-HDAC8 is bell-shaped with two pKa values of 7.4 and 10.0. The upper pKa reflects the ionization of the metal-bound water molecule and shifts to 9.1 in Zn(II)-HDAC8. The H142A mutant has activit...
-
general base general acid catalysis in human histone deacetylase 8
Biochemistry, 2016Co-Authors: Sister Lucy M Gantt, David W. Christianson, Christophe Decroos, Matthew S Lee, Laura E. Gullett, Christine M. Bowman, Carol A. FierkeAbstract:Histone deacetylases (HDACs) regulate cellular processes such as differentiation and apoptosis and are targeted by anticancer therapeutics in development and in the clinic. HDAC8 is a metal-dependent class I HDAC and is proposed to use a general acid–base catalytic pair in the mechanism of amide bond hydrolysis. Here, we report site-directed mutagenesis and enzymological measurements to elucidate the catalytic mechanism of HDAC8. Specifically, we focus on the catalytic function of Y306 and the histidine-aspartate dyads H142-D176 and H143-D183. Additionally, we report X-ray crystal structures of four representative HDAC8 mutants: D176N, D176N/Y306F, D176A/Y306F, and H142A/Y306F. These structures provide a useful framework for understanding enzymological measurements. The pH dependence of kcat/KM for wild-type Co(II)-HDAC8 is bell-shaped with two pKa values of 7.4 and 10.0. The upper pKa reflects the ionization of the metal-bound water molecule and shifts to 9.1 in Zn(II)-HDAC8. The H142A mutant has activit...
Antônio R. Panizzi - One of the best experts on this subject based on the ideXlab platform.
-
Aging and food source effects on mandibular stylets teeth wear of phytophagous stink bug (Heteroptera: Pentatomidae)
Neotropical entomology, 2010Co-Authors: Rogério A. Depieri, Fábio Siqueira, Antônio R. PanizziAbstract:Studies were conducted to test the effect of age and food sources on wear of the mandibular teeth of the phytophagous pentatomid, Euschistus heros (F.). The total length (µm) of the area bearing the mandibular teeth, the length of the 1st tooth, and the height of the 2nd tooth for Teneral (< 1 day-old) adults were significantly greater than that of adults fed on natural [green bean, Phaseolus vulgaris pods, raw shelled peanuts, Arachis hypogaea, and mature soybean, Glycine max seeds] for 30 or 60 days. Adults fed on artificial dry diet showed, in general, similar results to those of Teneral adults. Force (Newtons) required penetrating the natural foods was significantly greater than that required penetrating the artificial diet. The greater hardness of the natural foods caused increased mandibular serration wear.
-
SYSTEMATICS, MORPHOLOGY AND PHYSIOLOGY Aging and Food Source Effects on Mandibular Stylets Teeth Wear of Phytophagous Stink Bug (Heteroptera: Pentatomidae)
2010Co-Authors: Rogério A. Depieri, Fábio Siqueira, Antônio R. PanizziAbstract:Studies were conducted to test the effect of age and food sources on wear of the mandibular teeth of the phytophagous pentatomid, Euschistus heros (F.). The total length (μm) of the area bearing the mandibular teeth, the length of the 1st tooth, and the height of the 2nd tooth for Teneral (< 1 day-old) adults were signifi cantly greater than that of adults fed on natural (green bean, Phaseolus vulgaris pods, raw shelled peanuts, Arachis hypogaea, and mature soybean, Glycine max seeds) for 30 or 60 days. Adults fed on artifi cial dry diet showed, in general, similar results to those of Teneral adults. Force (Newtons) required penetrating the natural foods was signifi cantly greater than that required penetrating the artifi cial diet. The greater hardness of the natural foods caused increased mandibular serration wear.
P. Van Den Bossche - One of the best experts on this subject based on the ideXlab platform.
-
The effect of starvation on the susceptibility of Teneral and non-Teneral tsetse flies to trypanosome infection.
Medical and veterinary entomology, 2006Co-Authors: C. Kubi, J. Van Den Abbeele, R. De Deken, Tanguy Marcotty, Pierre Dorny, P. Van Den BosscheAbstract:Transmission of vector-borne diseases depends largely on the ability of the insect vector to become infected with the parasite. In tsetse flies, newly emerged or Teneral flies are considered the most likely to develop a mature, infective trypanosome infection. This was confirmed during experimental infections where laboratory-reared Glossina morsitans morsitans Westwood (Diptera: Glossinidae) were infected with Trypanosoma congolense or T. brucei brucei. The ability of mature adult tsetse flies to become infected with trypanosomes was significantly lower than that of newly emerged flies for both parasites. However, the nutritional status of the tsetse at the time of the infective bloodmeal affected its ability to acquire either a T. congolense or T. b. brucei infection. Indeed, an extreme period of starvation (3–4 days for Teneral flies, 7 days for adult flies) lowers the developmental barrier for a trypanosome infection, especially at the midgut level of the tsetse fly. Adult G. m. morsitans became at least as susceptible as newly emerged flies to infection with T. congolense. Moreover, the susceptibility of adult flies, starved for 7
Mary C Thomas - One of the best experts on this subject based on the ideXlab platform.
-
the general transcription machinery and general cofactors
Critical Reviews in Biochemistry and Molecular Biology, 2006Co-Authors: Mary C Thomas, Cheng Ming ChiangAbstract:ABSTRACTIn eukaryotes, the core promoter serves as a platform for the assembly of transcription preinitiation complex (PIC) that includes TFIIA, TFIIB, TFIID, TFIIE, TFIIF, TFIIH, and RNA polymerase II (pol II), which function collectively to specify the transcription start site. PIC formation usually begins with TFIID binding to the TATA box, initiator, and/or downstream promoter element (DPE) found in most core promoters, followed by the entry of other general transcription factors (GTFs) and pol II through either a sequential assembly or a preassembled pol II holoenzyme pathway. Formation of this promoter-bound complex is sufficient for a basal level of transcription. However, for activator-dependent (or regulated) transcription, general cofactors are often required to transmit regulatory signals between gene-specific activators and the general transcription machinery. Three classes of general cofactors, including TBP-associated factors (TAFs), Mediator, and upstream stimulatory activity (USA)-derived ...
-
The general transcription machinery and general cofactors.
Critical Reviews in Biochemistry and Molecular Biology, 2006Co-Authors: Mary C Thomas, Cheng Ming ChiangAbstract:ABSTRACTIn eukaryotes, the core promoter serves as a platform for the assembly of transcription preinitiation complex (PIC) that includes TFIIA, TFIIB, TFIID, TFIIE, TFIIF, TFIIH, and RNA polymerase II (pol II), which function collectively to specify the transcription start site. PIC formation usually begins with TFIID binding to the TATA box, initiator, and/or downstream promoter element (DPE) found in most core promoters, followed by the entry of other general transcription factors (GTFs) and pol II through either a sequential assembly or a preassembled pol II holoenzyme pathway. Formation of this promoter-bound complex is sufficient for a basal level of transcription. However, for activator-dependent (or regulated) transcription, general cofactors are often required to transmit regulatory signals between gene-specific activators and the general transcription machinery. Three classes of general cofactors, including TBP-associated factors (TAFs), Mediator, and upstream stimulatory activity (USA)-derived ...
