The interaction of protein structure, selection, and recombination on the evolution of the type-1 fimbrial major subunit (fimA) from Escherichia coli
The interaction of protein structure, selection, and recombination on the evolution of the type-1 fimbrial major subunit (fimA) from Escherichia coli
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DOI：
10.1007/s002390010148
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发表时间：
2001-02-01
影响因子：
3.9
通讯作者：
Gaut, BS
中科院分区：
文献类型：
--
作者：
Peek, AS;Souza, V;Gaut, BS
菌毛粘附素允许细菌与其环境相互作用并附着于其环境。细菌可能从这些相互作用中受益，但包括粘附素在内的所有外部结构也允许细菌被其他生物识别。因此粘附分子可能。在多种形式的选择下，包括限制功能相互作用或进化新表位以避免识别的选择。我们通过研究大肠杆菌1型菌毛主要亚基fimA的遗传多样性来解决这些问题。总体而言，fimA的序列多样性相对于其他E. coli基因。高多样性是正多样性选择的函数，如通过d（N）/d（S）比高于1.0所检测到的，并且经受多样性选择的氨基酸残基非随机地聚集在肽的外表面上。此外，McDonald和Kreitman测试表明，在大肠杆菌之间的fimA处存在历史上的但不是当前的定向选择。大肠杆菌和沙门氏菌。最后，fimA肽的某些区域似乎在E.大肠杆菌，特别是参与亚基与亚基相互作用的分子内部区域。突变也在大肠杆菌fimA等位基因变异中起主要作用，重组（2N（e）c）和突变（2N（e）mu）的估计值大致相同。分离作用可用于分离fimA肽的不同区域中的不同进化力。
Fimbrial adhesins allow bacteria to interact with and attach to their environment. The bacteria possibly benefit from these interactions, but all external structures including adhesins also allow bacteria to be identified by other organisms. Thus adhesion molecules might. be under multiple forms of selection including selection to constrain functional interactions or evolve novel epitopes to avoid recognition. We address these issues by studying genetic diversity in the Escherichia coli type-1 fimbrial major subunit, fimA. Overall, sequence diversity in fimA is high (pi = 0.07) relative to that in other E. coli genes. High diversity is a function of positive diversifying selection, as detected by d(N)/d(S) ratios higher than 1.0, and amino acid residuces subject to diversifying selection are nonrandomly clustered on the exterior surface of the peptide, In addition, McDonald and Kreitman tests suggest that there has been historical but not current directional selection at fimA between E. coli and Salmonella. Finally, some regions of the fimA peptide appear to be under strong structural constraint within E. coli, particularly the interior regions of the molecule that is involved in subunit to subunit interaction. Recombination also plays a major role contributing to E, coli fimA allelic variation and estimates of recombination (2N(e)c) and mutation (2N(e)mu) are about the same. Recombination may act to separate the diverse evolutionary forces in different regions of the fimA peptide.