Denamur E, Lecointre G, Darlu P, Tenaillon O, Acquaviva C, Sayada C, Sunjevaric I, Rothstein R, Elion J, Taddei F, Radman M, Matic I
INSERM U 458 Hôpital Robert Debré 48 boulevard Sérurier 75935 Cedex 19, Paris, France.
Cell. 2000 Nov 22;103(5):711-21. doi: 10.1016/s0092-8674(00)00175-6.
Mutation and subsequent recombination events create genetic diversity, which is subjected to natural selection. Bacterial mismatch repair (MMR) deficient mutants, exhibiting high mutation and homologous recombination rates, are frequently found in natural populations. Therefore, we have explored the possibility that MMR deficiency emerging in nature has left some "imprint" in the sequence of bacterial genomes. Comparative molecular phylogeny of MMR genes from natural Escherichia coli isolates shows that, compared to housekeeping genes, individual functional MMR genes exhibit high sequence mosaicism derived from diverse phylogenetic lineages. This apparent horizontal gene transfer correlates with hyperrecombination phenotype of MMR-deficient mutators. The sequence mosaicism of MMR genes may be a hallmark of a mechanism of adaptive evolution that involves modulation of mutation and recombination rates by recurrent losses and reacquisitions of MMR gene functions.
突变及随后的重组事件创造了遗传多样性，而这种多样性会受到自然选择的影响。在自然种群中经常能发现细菌错配修复（MMR）缺陷型突变体，它们表现出高突变率和同源重组率。因此，我们探讨了自然界中出现的MMR缺陷是否在细菌基因组序列中留下了一些“印记”的可能性。对来自自然大肠杆菌分离株的MMR基因进行比较分子系统发育分析表明，与管家基因相比，单个功能性MMR基因表现出源自不同系统发育谱系的高序列镶嵌性。这种明显的水平基因转移与MMR缺陷型突变体的高重组表型相关。MMR基因的序列镶嵌性可能是一种适应性进化机制的标志，该机制涉及通过MMR基因功能的反复丧失和重新获得来调节突变率和重组率。
