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The ? enigma: bacterial ? factors, archaeal TFB and eukaryotic TFIIB are homologs.

ABSTRACT: Structural comparisons of initiating RNA polymerase complexes and structure-based amino acid sequence alignments of general transcription initiation factors (eukaryotic TFIIB, archaeal TFB and bacterial ? factors) show that these proteins are homologs. TFIIB and TFB each have two-five-helix cyclin-like repeats (CLRs) that include a C-terminal helix-turn-helix (HTH) motif (CLR/HTH domains). Four homologous HTH motifs are present in bacterial ? factors that are relics of CLR/HTH domains. Sequence similarities clarify models for ? factor and TFB/TFIIB evolution and function and suggest models for promoter evolution. Commitment to alternate modes for transcription initiation appears to be a major driver of the divergence of bacteria and archaea.

SUBMITTER: Burton SP

PROVIDER: S-EPMC4581349 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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The σ enigma: bacterial σ factors, archaeal TFB and eukaryotic TFIIB are homologs.

Burton Samuel P SP Burton Zachary F ZF

Transcription 20140101 4

Structural comparisons of initiating RNA polymerase complexes and structure-based amino acid sequence alignments of general transcription initiation factors (eukaryotic TFIIB, archaeal TFB and bacterial σ factors) show that these proteins are homologs. TFIIB and TFB each have two-five-helix cyclin-like repeats (CLRs) that include a C-terminal helix-turn-helix (HTH) motif (CLR/HTH domains). Four homologous HTH motifs are present in bacterial σ factors that are relics of CLR/HTH domains. Sequence ...[more]

PMID: 25483602

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