Genes for the cytoskeletal protein tubulin in the bacterial genus Prosthecobacter
Genes for the cytoskeletal protein tubulin in the bacterial genus Prosthecobacter
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DOI：
10.1073/pnas.012516899
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发表时间：
2002-12-24
影响因子：
11.1
通讯作者：
Staley, JT
中科院分区：
文献类型：
--
作者：
Jenkins, C;Samudrala, R;Staley, JT
微管蛋白是微管细胞骨架的蛋白质成分，存在于所有已知的真核生物中，但从未在细菌或古细菌中发现。在这里，我们报告了 Prosthecobacter 属（疣微菌科）细菌中存在两种微管蛋白样基因 [细菌微管蛋白 a (btuba) 和细菌微管蛋白 b (btubb)]。在这项研究中，我们研究了这些基因的组织和表达，并对细菌和真核蛋白质序列进行了比较分析，重点关注它们的系统发育和 3D 结构。 btuba 和 btubb 基因与驱动蛋白轻链基因同源物一起排列为基因组内的相邻基因座。 RT-PCR 实验表明这三个基因是共转录的，并且在 btuba 上游鉴定出了一个可能的启动子。根据比较建模数据，我们预测Prosthecobacter微管蛋白是单体的，与真核α和β微管蛋白不同，后者形成二聚体，因此不太可能形成微管样结构。系统发育分析表明，微管蛋白修复杆菌差异很大，不支持最近来自真核生物的基因水平转移。细菌属中微管蛋白基因的发现可能为细胞骨架的进化提供新的见解。
Tubulins, the protein constituents of the microtubule cytoskeleton, are present in all known eukaryotes but have never been found in the Bacteria or Archaea. Here we report the presence of two tubulin-like genes [bacterial tubulin a (btuba) and bacterial tubulin b (btubb)] in bacteria of the genus Prosthecobacter (Division Verrucomicrobia). In this study, we investigated the organization and expression of these genes and conducted a comparative analysis of the bacterial and eukaryotic protein sequences, focusing on their phylogeny and 3D structures. The btuba and btubb genes are arranged as adjacent loci within the genome along with a kinesin light chain gene homolog. RT-PCR experiments indicate that these three genes are cotranscribed, and a probable promoter was identified upstream of btuba. On the basis of comparative modeling data, we predict that the Prosthecobacter tubulins are monomeric, unlike eukaryotic alpha and beta tubulins, which form dimers and are therefore unlikely to form microtubule-like structures. Phylogenetic analyses indicate that the Prosthecobacter tubulins are quite divergent and do not support recent horizontal transfer of the genes from a eukaryote. The discovery of genes for tubulin in a bacterial genus may offer new insights into the evolution of the cytoskeleton.