Whole-genome analyses of speciation events in pathogenic Brucellae
Whole-genome analyses of speciation events in pathogenic Brucellae
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DOI：
10.1128/iai.73.12.8353-8361.2005
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发表时间：
2005-12-01
影响因子：
3.1
通讯作者：
Garcia, E
中科院分区：
文献类型：
--
作者：
Chain, PSG;Comerci, DJ;Garcia, E
尽管它们的DNA同源性很高，并有建议将经典的布鲁氏菌物种归类为布鲁氏菌的生物群，但公认的布鲁氏菌物种可以通过不同的生化和脂肪酸特征以及明显的宿主范围来区分(例如，猪布鲁氏菌、绵羊和山羊的羊布鲁氏菌，以及牛的布鲁氏菌流产)。在这里，我们介绍了B.bortus 2308，毒力原型生物群I株的基因组，以及它与另外两个人类致病性布鲁氏菌物种和B.bortus野外分离株9-941的比较。假基因、缺失和插入的全球分布支持了早先的迹象，即流产杆菌和山羊杆菌有一个共同的祖先，是从猪瘟病毒分化而来的。除了十几个基因外，两个流产杆菌菌株的基因互补是相同的，而三个物种在基因含量和假基因上不同。影响转录调节因子和外膜蛋白的物种特异性基因失活模式表明，这些失活可能在宿主特异性的建立中发挥重要作用，并可能是布鲁氏菌物种形成的主要驱动因素。尽管布鲁氏菌不活动，但它含有鞭毛基因簇，并显示物种特有的鞭毛基因失活，这可能导致不同版本的鞭毛衍生结构的产生，并可能导致宿主特异性和毒力的差异。代谢变化，例如缺乏合成多种化合物(如糖原、生物素、NAD和胆碱)的完整代谢途径，与布鲁氏菌对细胞内生活方式的适应是一致的。
Despite their high DNA identity and a proposal to group classical Brucella species as biovars of Brucella melitensis, the commonly recognized Brucella species can be distinguished by distinct biochemical and fatty acid characters, as well as by a marked host range (e.g., Brucella suis for swine, B. melitensis for sheep and goats, and Brucella abortus for cattle). Here we present the genome of B. abortus 2308, the virulent prototype biovar I strain, and its comparison to the two other human pathogenic Brucella species and to B. abortus field isolate 9-941. The global distribution of pseudogenes, deletions, and insertions supports previous indications that B. abortus and B. melitensis share a common ancestor that diverged from B. suis. With the exception of a dozen genes, the genetic complements of both B. abortus strains are identical, whereas the three species differ in gene content and pseudogenes. The pattern of species-specific gene inactivations affecting transcriptional regulators and outer membrane proteins suggests that these inactivations may play an important role in the establishment of host specificity and may have been a primary driver of speciation in the genus Brucella. Despite being nonmotile, the brucellae contain flagellum gene clusters and display species-specific flagellar gene inactivations, which lead to the putative generation of different versions of flagellum-derived structures and may contribute to differences in host specificity and virulence. Metabolic changes such as the lack of complete metabolic pathways for the synthesis of numerous compounds (e.g., glycogen, biotin, NAD, and choline) are consistent with adaptation of brucellae to an intracellular life-style.