Identification and characterization of the capsular polysaccharide (K-antigen) locus of Porphyromonas gingivalis
Identification and characterization of the capsular polysaccharide (K-antigen) locus of Porphyromonas gingivalis
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DOI：
10.1128/iai.74.1.449-460.2006
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发表时间：
2006-01-01
影响因子：
3.1
通讯作者：
Curtis, MA
中科院分区：
文献类型：
--
作者：
Aduse-Opoku, J;Slaney, JM;Curtis, MA
革兰氏阴性菌的荚膜多糖在恶劣环境中维持细胞结构完整性方面起着重要作用，并且由于它们在给定物种中的多样性，可以作为有用的分类辅助手段。为了表征口腔革兰氏阴性菌牙龈卟啉单胞菌（Porphyromonas gingivalis）中荚膜生物合成的遗传位点，我们分析了牙龈卟啉单胞菌（Porphyromonas gingivalis）W83的基因组，基于与其他细菌中的荚膜编码位点的比较，发现在PG 0106-PG 0120和PG 1135-PG 1142处的两个候选位点具有足够的编码能力和适当的基因功能。在PG 0106-PG 0120处制备牙龈卟啉单胞菌W50-a K1血清型的插入和缺失突变体。PG 0109-PG 9118和PG 0116-PG 0120的缺失均产生不再与K1血清型的抗血清反应的突变体。代表所有6种K抗原血清型和K-菌株的菌株中基因座的限制性片段长度多态性分析表明血清型之间存在显著差异，血清型内保守性有限。相比之下，PG 1135-PG 1142在该菌株集合中高度保守。菌株381（K-菌株）中荚膜基因座的序列分析表明与W83基因座同线性，但也存在显著差异，包括用三个独特的开放阅读框替换PG 0109-PG 0110、缺失PG 0112-PG 0114和PG 0106内的内部终止密码子，这些都可能导致该菌株中荚膜表达的缺失。对菌株W50的荚膜突变体中的Arg-牙龈卟啉菌蛋白酶的分析显示，这些酶的聚糖修饰没有显著变化，这表明牙龈卟啉单胞菌中的糖基化装置不依赖于荚膜生物合成机制。
Capsular polysaccharides of gram-negative bacteria play an important role in maintaining the structural integrity of the cell in hostile environments and, because of their diversity within a given species, can act as useful taxonomic aids. In order to characterize the genetic locus for capsule biosynthesis in the oral gram-negative bacterium Porphyromonas gingivalis, we analyzed the genome of P. gingivalis W83 which revealed two candidate loci at PG0106-PG0120 and PG1135-PG1142 with sufficient coding capacity and appropriate gene functions based on comparisons with capsule-coding loci in other bacteria. Insertion and deletion mutants were prepared at PG0106-PG0120 in P. gingivalis W50-a K1 serotype. Deletion of PG0109-PG9118 and PG0116-PG0120 both yielded mutants which no longer reacted with antisera to K1 serotypes. Restriction fragment length polymorphism analysis of the locus in strains representing all six K-antigen serotypes and K- strains demonstrated significant variation between serotypes and limited conservation within serotypes. In contrast, PG1135-PG1142 was highly conserved in this collection of strains. Sequence analysis of the capsule locus in strain 381 (K- strain) demonstrated synteny with the W83 locus but also significant differences including replacement of PG0109-PG0110 with three unique open reading frames, deletion of PG0112-PG0114, and an internal termination codon within PG0106, each of which could contribute to the absence of capsule expression in this strain. Analysis of the Arg-gingipains in the capsule mutants of strain W50 revealed no significant changes to the glycan modifications of these enzymes, which indicates that the glycosylation apparatus in P. gingivalis is independent of the capsule biosynthetic machinery.