Structure of TFIIK for phosphorylation of CTD of RNA polymerase II.
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ABSTRACT:
SUBMITTER: van Eeuwen T
PROVIDER: S-EPMC8026125 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:TFIIH is a 10-protein complex that is conserved through out eukaryotes. TFIIH has two primary cellular functions: transcription initiation and nucleotide excision repair (NER). In transcription initiation, TFIIH acts as a structural scaffold, phosphorylates the RNA polymerase II (pol II) C-terminal domain (CTD) and translocates promoter DNA through the pol II active site to facilitate start site selection. In NER, again is a structural scaffold, opens a bubble around damaged DNA and scans the damaged strand for bulky lesions. In yeast (Saccharomyces cerevisiae), TFIIH is composed of the two helicases Ssl2 and Rad3, the scaffolding subunits Tfb1, Tfb2, Tfb4 and Ssl1 and the kinase subunits Kin28, Ccl1 and Tfb3.
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Project description:Kinases and phosphatases regulate mRNA synthesis and processing by phosphorylating and dephosphorylating the C-terminal domain (CTD) of the largest subunit of RNA polymerase II. Fcp1 is an essential CTD phosphatase that preferentially hydrolyzes Ser2-PO(4) of the tandem YSPTSPS CTD heptad array. Fcp1 crystal structures were captured at two stages of the reaction pathway: a Mg-BeF(3) complex that mimics the aspartylphosphate intermediate and a Mg-AlF(4)(-) complex that mimics the transition state of the hydrolysis step. Fcp1 is a Y-shaped protein composed of an acylphosphatase domain located at the base of a deep canyon formed by flanking modules that are missing from the small CTD phosphatase (SCP) clade: an Fcp1-specific helical domain and a C-terminal BRCA1 C-terminal (BRCT) domain. The structure and mutational analysis reveals that Fcp1 and Scp1 (a Ser5-selective phosphatase) adopt different CTD-binding modes; we surmise the CTD threads through the Fcp1 canyon to access the active site.
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