Genomic analysis of Bacteroides fragilis reveals extensive DNA inversions regulating cell surface adaptation
Genomic analysis of Bacteroides fragilis reveals extensive DNA inversions regulating cell surface adaptation
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DOI：
10.1073/pnas.0404172101
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发表时间：
2004-10-12
影响因子：
11.1
通讯作者：
Ohnishi, Y
中科院分区：
文献类型：
--
作者：
Kuwahara, T;Yamashita, A;Ohnishi, Y
类杆菌是人类结肠的主要共生菌，但主要致病种脆弱类杆菌(BF)与粘膜表面密切相关，而第二大类杆菌(Bt)则集中在结肠内。通过对BF基因组序列的测定和与Bt的比较分析，我们发现它们在基因组中存在相应的差异。这两个物种都获得了两种机制，有助于它们在结肠微生物区系中占据主导地位：通过基因扩增利用广泛的饮食多糖的特殊能力，以及通过多个DNA倒置系统创造可变表面抗原性的能力。然而，与Bt的内部定位一致，Bt对多糖同化的基因扩增更为发达。相反，在BF中，外部抗原结构可以更系统地改变。因此，在黏膜表面，微生物遇到宿主防御的持续攻击，有利于BF逃避免疫系统，增加其定植和感染潜力。
Bacteroides are predominant human colonic commensals, but the principal pathogenic species, Bacteroides fragilis (BF), lives closely associated with the mucosal surface, whereas a second major species, Bacteroides thetaiotaomicron (BT), concentrates within the colon. We find corresponding differences in their genomes, based on determination of the genome sequence of BF and comparative analysis with BT. Both species have acquired two mechanisms that contribute to their dominance among the colonic microbiota: an exceptional capability to use a wide range of dietary polysaccharides by gene amplification and the capacity to create variable surface antigenicities by multiple DNA inversion systems. However, the gene amplification for polysaccharide assimilation is more developed in BT, in keeping with its internal localization. In contrast, external antigenic structures can be changed more systematically in BF. Thereby, at the mucosal surface, where microbes encounter continuous attack by host defenses, BF evasion of the immune system is favored, and its colonization and infectious potential are increased.