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首页> 外文期刊>Journal of bacteriology >Evolution of the Major Pilus Gene Cluster ofHaemophilus influenzae
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Evolution of the Major Pilus Gene Cluster ofHaemophilus influenzae

机译：流感嗜血杆菌主要Pilus基因簇的演变

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Haemophilus influenzae is a ubiquitous colonizer of the human respiratory tract and causes diseases ranging from otitis media to meningitis. Many H. influenzae isolates express pili (fimbriae), which mediate adherence to epithelial cells and facilitate colonization. The pilus gene (hif) cluster of H. influenzae type b maps between purE andpepN and resembles a pathogenicity island: it is present in invasive strains, absent from the nonpathogenic Rd strain, and flanked by direct repeats of sequence at the insertion site. To investigate the evolution and role in pathogenesis of the hif cluster, we compared the purE-pepN regions of various H. influenzae laboratory strains and clinical isolates. Unlike Rd, most strains had an insert at this site, which usually was the only chromosomal locus of hif DNA. The inserts are diverse in length and organization: among 20 strains, nine different arrangements were found. Several nontypeable isolates lack hif genes but have two conserved open reading frames (hicA andhicB) upstream of purE; their inferred products are small proteins with no data bank homologs. Other isolates havehif genes but lack hic DNA or have combinations of hif and hic genes. By comparing these arrangements, we have reconstructed a hypothetical ancestral genotype, the extended hif cluster. The hif region of INT1, an invasive nontypeable isolate, resembles the hypothetical ancestor. We propose that a progenitor strain acquired the extended cluster by horizontal transfer and that other variants arose as deletions. The structure of the hif cluster may correlate with colonization site or pathogenicity.
机译：流感嗜血杆菌是人类呼吸道的普遍定居者，引起从中耳炎到脑膜炎的各种疾病。许多 H。流感分离株表达菌毛（菌毛），它介导对上皮细胞的粘附并促进定植。 H的菌毛基因（ hif ）簇。 b型流感在 purE 和 pepN 之间定位，类似于一个致病岛：它存在于侵袭性菌株中，非致病性Rd菌株不存在，而侧翼为直接在插入位点重复序列。为了研究 hif 簇的进化及其在发病机理中的作用，我们比较了各种 H的 purE-pepN 区。流感实验室菌株和临床分离株。与Rd不同，大多数菌株在此位点具有插入片段，通常是 hif DNA的唯一染色体基因座。插入片段的长度和组织各不相同：在20个菌株中，发现了9种不同的排列。几个不可分型的分离株缺乏 hif 基因，但在 purE 上游有两个保守的开放阅读框（ hicA 和 hicB ）;它们的推论产物是没有数据库同源物的小蛋白质。其他分离株具有 hif 基因，但缺乏 hic DNA或具有 hif 和 hic 基因的组合。通过比较这些安排，我们重建了一个假设的祖先基因型，扩展的 hif 簇。 INT1的 hif 区是一种侵入性不可分型的隔离株，与假设的祖先相似。我们建议祖细胞菌株通过水平转移获得了扩展的群集，其他变体作为删除出现。 hif 簇的结构可能与定殖位点或致病性有关。

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