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RNA polymerase III-specific general transcription factor IIIC contains a heterodimer resembling TFIIF Rap30/Rap74.

ABSTRACT: Transcription of tRNA-encoding genes by RNA polymerase (Pol) III requires the six-subunit general transcription factor IIIC that uses subcomplexes ?A and ?B to recognize two gene-internal promoter elements named A- and B-box. The Schizosaccharomyces pombe ?A 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 ?-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 ?A resemble the recognition of promoters by bacterial RNA polymerase, where ? 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.

SUBMITTER: Taylor NM

PROVIDER: S-EPMC3799434 | biostudies-literature | 2013 Oct

REPOSITORIES: biostudies-literature

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RNA polymerase III-specific general transcription factor IIIC contains a heterodimer resembling TFIIF Rap30/Rap74.

Taylor Nicholas M I NM Baudin Florence F von Scheven Gudrun G Müller Christoph W CW

Nucleic acids research 20130805 19

Transcription of tRNA-encoding genes by RNA polymerase (Pol) III requires the six-subunit general transcription factor IIIC that uses subcomplexes τA and τB to recognize two gene-internal promoter elements named A- and B-box. The Schizosaccharomyces pombe τA 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-termin ...[more]

PMID: 23921640

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Project description:All sequenced genomes of representatives of the Francisella genus contain two rpoA genes, which encode non-identical RNA polymerase (RNAP) subunits, ?1 and ?2. In all other bacteria studied to date, a dimer of identical ? subunits initiates the assembly of the catalytically proficient RNAP core (subunit composition ?2??'). Based on an observation that both ?1 and ?2 are incorporated into Francisella RNAP, Charity et al. (2007) previously suggested that up to four different species of RNAP core enzyme might form in the same Francisella cell.By in vitro assembly from fully denatured state, we determined that both Francisella ? subunits are required for efficient dimerization; no homodimer formation was detected. Bacterial two-hybrid system analysis likewise indicated strong interactions between the ?1 and ?2 N-terminal domains (NTDs, responsible for dimerization). NTDs of ?2 did not interact detectably, while weak interaction between ?1 NTDs was observed. This weak homotypic interaction may explain low-level transcription activity observed in in vitro RNAP reconstitution reactions containing Francisella large subunits (?', ?) and ?1. No activity was observed with RNAP reconstitution reactions containing ?2, while robust transcription activity was detected in reactions containing ?1 and ?2. Phylogenetic analysis based on RpoA resulted in a tree compatible with standard bacterial taxonomy with both Francisella RpoA branches positioned within ?-proteobacteria. The observed phylogeny and analysis of constrained trees are compatible with Francisella lineage-specific rpoA duplication followed by acceleration of evolutionary rate and subfunctionalization.The results strongly suggest that most Francisella RNAP contains ? heterodimer with a minor subfraction possibly containing ?1 homodimer. Comparative sequence analysis suggests that this heterodimer is oriented, in a sense that only one monomer, ?1, interacts with the ? subunit during the ?2? RNAP subassembly formation. Most likely the two rpoA copies in Francisella have emerged through a lineage-specific duplication followed by subfunctionalization of interacting paralogs.

Dataset Information

RNA polymerase III-specific general transcription factor IIIC contains a heterodimer resembling TFIIF Rap30/Rap74.

Publications

RNA polymerase III-specific general transcription factor IIIC contains a heterodimer resembling TFIIF Rap30/Rap74.

Similar Datasets

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