Hair Pamela S, Ward Michael D, Semmes O John, Foster Timothy J, Cunnion Kenji M
Department of Pediatrics,George L. Wright, Jr., Center for Biomedical Proteomics, Eastern Virginia Medical School, Norfolk, Virginia, USA.
J Infect Dis. 2008 Jul 1;198(1):125-33. doi: 10.1086/588825.
The human complement system plays an important role in the control of Staphylococcus aureus infection. For instance, we previously demonstrated that the central complement component deposited on the organism's surface, C3b, can be cleaved by the host complement control protein, factor I, resulting in diminished phagocytosis of S. aureus. In the present study, we have identified clumping factor A (ClfA) from cell wall proteins of S. aureus as a specific protein bound by factor I. Recombinant ClfA (rClfA) containing the full-length A region (peptides 40-559) also bound factor I. We identified an 50-kDa fragment of ClfA that is shed by S. aureus into growth medium. The shed ClfA fragment was derived from the A region of ClfA and bound factor I. rClfA and the shed ClfA fragment increased factor I cleavage of C3b into inactive C3b. Our findings describe a new S. aureus mechanism for modification of host complement activities.
人类补体系统在控制金黄色葡萄球菌感染中发挥着重要作用。例如，我们之前证明沉积在生物体表面的补体中心成分C3b可被宿主补体控制蛋白I因子裂解，导致金黄色葡萄球菌的吞噬作用减弱。在本研究中，我们从金黄色葡萄球菌的细胞壁蛋白中鉴定出聚集因子A（ClfA）作为I因子结合的特异性蛋白。包含全长A区域（肽段40 - 559）的重组ClfA（rClfA）也能结合I因子。我们鉴定出一个50 kDa的ClfA片段，它由金黄色葡萄球菌释放到生长培养基中。释放的ClfA片段源自ClfA的A区域并能结合I因子。rClfA和释放的ClfA片段增加了I因子将C3b裂解为无活性C3b的能力。我们的研究结果描述了一种金黄色葡萄球菌改变宿主补体活性的新机制。
