Department of Microbiology and Immunology, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China.
Med Microbiol Immunol. 2012 Feb;201(1):81-92. doi: 10.1007/s00430-011-0208-z. Epub 2011 Jun 24.
Staphylococcus aureus is an important human pathogen that causes a variety of diseases, ranging from localized skin infections to life-threatening systemic infections. The success of S. aureus as a pathogen is partly due to its ability to adhere to a wide range of host tissues by binding to host extracellular matrix proteins such as fibrinogen, fibronectin, and collagen. Staphylococcus aureus expresses two proteins that can bind specifically to fibrinogen, clumping factors A and B (ClfA and ClfB). Repressor of toxins (Rot) is known to be a global regulator of virulence gene expression in S. aureus. The translation of Rot is regulated by the staphylococcal accessory gene regulator (Agr) quorum-sensing system. In this study, we demonstrated that Rot and the Agr system in S. aureus NCTC8325 can affect the bacterial binding ability to human fibrinogen (Fg) under different bacterial growth phases. Our real-time RT-PCR results indicated that both Rot and the Agr system have no significant effect on clfA expression. However, Rot is an activator of clfB, and Agr/RNAIII can regulate clfB expression via Rot. Gel shift data further suggested that Rot might regulate clfB expression by directly binding to the promoter region of clfB. Moreover, Rot and the Agr system exhibited consistent regulatory effects on clfB transcription and bacterial Fg-binding ability, suggesting that Rot and the Agr system might affect bacterial Fg-binding ability mainly through regulating clfB transcription.
金黄色葡萄球菌是一种重要的人类病原体，可引起多种疾病，从局部皮肤感染到危及生命的全身感染。金黄色葡萄球菌作为病原体的成功部分归因于其通过与纤维蛋白原、纤维连接蛋白和胶原蛋白等宿主细胞外基质蛋白结合来黏附宿主组织的能力。金黄色葡萄球菌表达两种可特异性结合纤维蛋白原的蛋白，即凝聚因子 A 和 B（ClfA 和 ClfB）。已知毒素抑制物（Rot）是金黄色葡萄球菌毒力基因表达的全局调控因子。Rot 的翻译受金黄色葡萄球菌辅助基因调控因子（Agr）群体感应系统调控。在本研究中，我们证明了金黄色葡萄球菌 NCTC8325 中的 Rot 和 Agr 系统可以在不同的细菌生长阶段影响细菌与人纤维蛋白原（Fg）的结合能力。我们的实时 RT-PCR 结果表明，Rot 和 Agr 系统对 clfA 的表达没有显著影响。然而，Rot 是 clfB 的激活剂，Agr/RNAIII 可以通过 Rot 调节 clfB 的表达。凝胶迁移数据进一步表明，Rot 可能通过直接结合 clfB 启动子区域来调节 clfB 的表达。此外，Rot 和 Agr 系统对 clfB 转录和细菌 Fg 结合能力表现出一致的调节作用，表明 Rot 和 Agr 系统可能主要通过调节 clfB 转录来影响细菌 Fg 结合能力。
