Dentipain, a Streptococcus pyogenes IdeS protease homolog, is a novel virulence factor of Treponema denticola.
Dentipain, a Streptococcus pyogenes IdeS protease homolog, is a novel virulence factor of Treponema denticola.
复制标题
DOI：
10.1515/bc.2010.113
复制
发表时间：
2010-09
影响因子：
3.7
通讯作者：
Potempa J
中科院分区：
文献类型：
--
作者：
Ishihara K;Wawrzonek K;Shaw LN;Inagaki S;Miyamoto M;Potempa J
齿垢密螺旋体是慢性牙周炎的主要病原体。对 T. denticola 基因组的分析揭示了一个与编码化脓性链球菌 (IdeS) 半胱氨酸蛋白酶的基因同源的基因。 IdeS 通过特异性切割 IgG 分子来干扰 IgG 依赖性调理吞噬作用。对这个基因（称为 ideT）的分析表明它编码一个两域蛋白。该蛋白的 N 末端由串联的免疫球蛋白样结构域和位于 C 末端的 IdeS 样蛋白酶结构域组成。我们在此表明，在分泌过程中，IdeT 蛋白被加工成 N 端片段，该片段仍与细胞结合，而 C 端部分则释放到培养基中。尽管 IdeT 的这个分泌结构域（称为牙本质蛋白酶）与 IdeS 蛋白酶仅显示 25% 的同一性，但假定的催化半胱氨酸和组氨酸残基是高度保守的。对重组牙本质蛋白酶的分析表明，它会裂解胰岛素 β 链，而这种活性会被半胱氨酸蛋白酶的诊断抑制剂 E-64 所抑制。除胰岛素外，未检测到其他蛋白质底物的裂解，表明牙本质蛋白酶具有寡肽酶活性。构建了带有修饰的 ideT 的突变菌株，其牙本质蛋白酶结构域被删除。在小鼠脓肿模型中，发现与亲本菌株相比，该突变体的脓肿形成活性显着降低，表明牙本质蛋白酶有助于 T. denticola 的毒力。
Treponema denticola is a major pathogen of chronic periodontitis. Analysis of the T. denticola genome revealed a gene orthologous with a gene encoding a cysteine protease from Streptococcus pyogenes (IdeS). IdeS interferes with IgG-dependent opsonophagocytosis by specific cleavage of IgG molecules. Analysis of this gene (termed ideT) revealed it to encode a two domain protein. The N-terminus of this protein is composed of a tandem, immunoglobulin-like domain, followed by a C-terminally located IdeS-like protease domain. We show here that during secretion the IdeT protein is processed into an N-terminal fragment which remains associated with the cell, and a C-terminal portion released into the medium. Although this secreted domain of IdeT, termed dentipain, shows only 25% identity with the IdeS protease, the putative catalytic cysteine and histidine residues are strongly conserved. Analysis of recombinant dentipain revealed that it cleaved the insulin β-chain, an activity which was inhibited by E-64, a diagnostic inhibitor of cysteine proteases. Apart from insulin no cleavage of other protein substrates was detected, suggesting that dentipain has oligopeptidase activity. A mutant strain was constructed bearing a modified ideT whose dentipain domain was deleted. This mutant was found to be significantly reduced in its abscess forming activity compared to the parental strain in a murine abscess model, suggesting that dentipain contributes to the virulence of T. denticola.