Chlenov Mark, Masuda Shoko, Murakami Katsuhiko S, Nikiforov Vadim, Darst Seth A, Mustaev Arkady
The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.
J Mol Biol. 2005 Oct 14;353(1):138-54. doi: 10.1016/j.jmb.2005.07.073.
The large beta and beta' subunits of the bacterial core RNA polymerase (RNAP) are highly conserved throughout evolution. Nevertheless, large sequence insertions in beta and beta' characterize specific evolutionary lineages of bacteria. The Thermus aquaticus RNAP beta' subunit contains a 283 residue insert between conserved regions A and B that is found in only four bacterial species. The Escherichia coli RNAP beta' subunit contains a 188 residue insert in the middle of conserved region G that is found in a wide range of bacterial species. Here, we present structural studies of these two beta' insertions. We show that the inserts comprise repeats of a previously characterized fold, the sandwich-barrel hybrid motif (as predicted from previous sequence analysis) and that the inserts serve significant roles in facilitating protein/protein and/or protein/nucleic acid interactions.
细菌核心RNA聚合酶（RNAP）的β和β'大亚基在整个进化过程中高度保守。然而，β和β'中的大片段序列插入是细菌特定进化谱系的特征。嗜热水生栖热袍菌RNAP的β'亚基在保守区域A和B之间有一个283个残基的插入序列，仅在四种细菌物种中发现。大肠杆菌RNAP的β'亚基在保守区域G的中间有一个188个残基的插入序列，在广泛的细菌物种中都能找到。在这里，我们展示了对这两个β'插入序列的结构研究。我们表明，这些插入序列包含先前已鉴定的折叠结构（三明治桶状杂合基序，如先前序列分析所预测）的重复序列，并且这些插入序列在促进蛋白质/蛋白质和/或蛋白质/核酸相互作用中发挥着重要作用。
