Lapirattanakul Jinthana, Nomura Ryota, Matsumoto-Nakano Michiyo, Srisatjaluk Ratchapin, Ooshima Takashi, Nakano Kazuhiko
Faculty of Dentistry, Mahidol University, Bangkok 10400, Thailand.
Osaka University Graduate School of Dentistry, Osaka 565-0871, Japan.
Int J Med Microbiol. 2015 May;305(3):383-91. doi: 10.1016/j.ijmm.2015.03.001. Epub 2015 Mar 6.
Streptococcus mutans, which consists of four serotypes, c, e, f, and k, possesses a 190-kDa cell surface protein antigen (PA) for initial tooth adhesion. We used Western blot analysis to determine PA expression in 750 S. mutans isolates from 150 subjects and found a significantly higher prevalence of the isolates with PA expression defects in serotypes f and k compared to serotypes c and e. Moreover, the defect patterns could be classified into three types; no PA expression on whole bacterial cells and in their supernatant samples (Type N1), PA expression mainly seen in supernatant samples (Type N2), and only low expression of PA in the samples of whole bacterial cells (Type W). The underlying reasons for the defects were mutations in the gene encoding PA as well as in the transcriptional processing of this gene for Type N1, defects in the sortase gene for Type N2, and low mRNA expression of PA for Type W. Since cellular hydrophobicity and phagocytosis susceptibility of the PA-defective isolates were significantly lower than those of the normal expression isolates, the potential implication of such defective isolates in systemic diseases involving bacteremia other than dental caries was suggested. Additionally, multilocus sequence typing was utilized to characterize S. mutans clones that represented a proportion of isolates with PA defects of 65-100%. Therefore, we described the molecular basis for variation defects in PA expression of S. mutans. Furthermore, we also emphasized the strong association between PA expression defects and serotypes f and k as well as the clonal relationships among these isolates.
变形链球菌由c、e、f和k四种血清型组成，拥有一种190 kDa的细胞表面蛋白抗原（PA）用于初始牙齿黏附。我们使用蛋白质印迹分析来确定来自150名受试者的750株变形链球菌分离株中PA的表达情况，发现与血清型c和e相比，血清型f和k中具有PA表达缺陷的分离株患病率显著更高。此外，缺陷模式可分为三种类型：全菌细胞及其上清液样本中均无PA表达（N1型），PA表达主要见于上清液样本（N2型），以及全菌细胞样本中PA仅低表达（W型）。这些缺陷的潜在原因是，对于N1型，编码PA的基因以及该基因的转录加工发生了突变；对于N2型，分选酶基因存在缺陷；对于W型，PA的mRNA表达较低。由于PA缺陷型分离株的细胞疏水性和吞噬易感性显著低于正常表达的分离株，提示这些缺陷型分离株在除龋齿外涉及菌血症的全身性疾病中可能具有潜在影响。此外，多位点序列分型被用于鉴定代表65 - 100%的PA缺陷分离株比例的变形链球菌克隆。因此，我们描述了变形链球菌PA表达变异缺陷的分子基础。此外，我们还强调了PA表达缺陷与血清型f和k之间的强关联以及这些分离株之间的克隆关系。
