4bjj
From Proteopedia
Sfc1-Sfc7 dimerization module
Structural highlights
FunctionSFC1_SCHPO TFIIIC mediates tRNA and 5S RNA gene activation by binding to intragenic promoter elements. Upstream of the transcription start site, TFIIIC assembles the initiation complex TFIIIB-TFIIIC-tDNA, which is sufficient for RNA polymerase III recruitment and function. Part of the tauA domain of TFIIIC that binds boxA DNA promoter sites of tRNA and similar genes. Participates in the interconnection of tauA with tauB via its contacts with sfc3 and sfc6. Serves as a scaffold critical for tauA-DNA spatial configuration and tauB-DNA stability. Localizes to chromatin insulator sequence without recruiting RNA polymerase III and plays a role in nuclear organization.[1] [2] Publication Abstract from PubMedTranscription of tRNA-encoding genes by RNA polymerase (Pol) III requires the six-subunit general transcription factor IIIC that uses subcomplexes tauA and tauB to recognize two gene-internal promoter elements named A- and B-box. The Schizosaccharomyces pombe tauA subcomplex comprises subunits Sfc1, Sfc4 and Sfc7. The crystal structure of the Sfc1/Sfc7 heterodimer reveals similar domains and overall domain architecture to the Pol II-specific general transcription factor TFIIF Rap30/Rap74. The N-terminal Sfc1/Sfc7 dimerization module consists of a triple beta-barrel similar to the N-terminal TFIIF Rap30/Rap74 dimerization module, whereas the C-terminal Sfc1 DNA-binding domain contains a winged-helix domain most similar to the TFIIF Rap30 C-terminal winged-helix domain. Sfc1 DNA-binding domain recognizes single and double-stranded DNA by an unknown mechanism. Several features observed for A-box recognition by tauA resemble the recognition of promoters by bacterial RNA polymerase, where sigma factor unfolds double-stranded DNA and stabilizes the non-coding DNA strand in an open conformation. Such a function has also been proposed for TFIIF, suggesting that the observed structural similarity between Sfc1/Sfc7 and TFIIF Rap30/Rap74 might also reflect similar functions. RNA polymerase III-specific general transcription factor IIIC contains a heterodimer resembling TFIIF Rap30/Rap74.,Taylor NM, Baudin F, von Scheven G, Muller CW Nucleic Acids Res. 2013 Aug 5. PMID:23921640[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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