Comparative genomics of microbial pathogens and symbionts
Comparative genomics of microbial pathogens and symbionts
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DOI：
10.1093/bioinformatics/18.suppl_2.s17
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发表时间：
2002-10-01
期刊：
影响因子：
5.8
通讯作者：
Tamas, I
中科院分区：
文献类型：
--
作者：
Andersson, SGE;Alsmark, C;Tamas, I
我们感兴趣的是量化基因获取、丢失、扩展和重排对微生物基因组进化的贡献。在这里，我们基于密切相关的菌株和具有不同生活方式的物种的成对基因组比较，讨论影响微生物基因组分歧的因素。特别关注立克次体、巴尔通体和布赫内拉属的细胞内病原体和共生体。广泛的基因丢失以及噬菌体和质粒库的获取受到限制可能可以解释为什么单宿主病原体通常不如多宿主病原体成功。我们注意到，物种特异性基因往往比直系同源基因短，这表明其中一部分可能代表化石-orf，这也得到了物种间多重序列比对的支持。我们的基因组比较结果被置于α和γ变形菌的系统发育分析的背景下。我们强调了由不同突变率和模式引起的假象，这表明非典型的系统发育位置不能先验地作为水平基因转移事件的证据。自由生活的微生物基因组结构的灵活性与蚜虫内共生体小基因组的极端稳定性形成鲜明对比，后者在过去 5000 万年里没有发生遗传物质的重排或流入 (1)。综上所述，结果表明基因组稳定性与重复序列和移动遗传元件的含量相关，从而间接与细菌的生活方式相关。
We are interested in quantifying the contribution of gene acquisition, loss, expansion and rearrangements to the evolution of microbial genomes. Here, we discuss factors influencing microbial genome divergence based on pair-wise genome comparisons of closely related strains and species with different lifestyles. A particular focus is on intracellular pathogens and symbionts of the generaRickettsia,BartonellaandBuchnera. Extensive gene loss and restricted access to phage and plasmid pools may provide an explanation for why single host pathogens are normally less successful than multihost pathogens. We note that species-specific genes tend to be shorter than orthologous genes, suggesting that a fraction of these may represent fossil-orfs, as also supported by multiple sequence alignments among species. The results of our genome comparisons are placed in the context of phylogenomic analyses of alpha and gamma proteobacteria. We highlight artefacts caused by different rates and patterns of mutations, suggesting that atypical phylogenetic placements can nota prioribe taken as evidence for horizontal gene transfer events. The flexibility in genome structure among free-living microbes contrasts with the extreme stability observed for the small genomes of aphid endosymbionts, in which no rearrangements or inflow of genetic material have occurred during the past 50 millions years (1). Taken together, the results suggest that genomic stability correlate with the content of repeated sequences and mobile genetic elements, and thereby indirectly with bacterial lifestyles.