The σ enigma: bacterial σ factors, archaeal TFB and eukaryotic TFIIB are homologs.
The σ enigma: bacterial σ factors, archaeal TFB and eukaryotic TFIIB are homologs.
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DOI：
10.4161/21541264.2014.967599
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Burton ZF
中科院分区：
文献类型：
--
作者：
Burton SP;Burton ZF
起始RNA聚合酶复合物的结构比较和一般转录起始因子（真核TFIIB、古细菌TFB和细菌σ因子）的基于结构的氨基酸序列比对表明，这些蛋白质是同源的。TFIIB和TFB各自具有包括C-末端螺旋-转角-螺旋（HTH）基序的2 - 5-螺旋细胞周期蛋白样重复序列（CLR）（TFIIB/HTH结构域）。在细菌σ因子中存在四个同源的HTH基序，它们是σ/HTH结构域的遗迹。序列相似性阐明了σ因子和TFB/TFIIB进化和功能的模型，并提出了启动子进化的模型。致力于转录起始的替代模式似乎是细菌和古细菌分歧的主要驱动力。
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 similarities clarify models for σ 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.