Su H, Zhang Y X, Barrera O, Watkins N G, Caldwell H D
Laboratory of Microbial Structure and Function, National Institute of Allergy and Infectious Diseases, Hamilton, Montana 59840.
Infect Immun. 1988 Aug;56(8):2094-100. doi: 10.1128/iai.56.8.2094-2100.1988.
The initial interaction of chlamydiae with host cells is not well understood. Chlamydial cell surface components that function in attachment are key virulence factors, and their identification is critical for understanding the pathogenic strategies of this very successful parasite. We used trypsin proteolysis of chlamydiae to define surface components that function in chlamydia-host cell interactions. We found that trypsin had a differential effect on the infectivity of Chlamydia trachomatis serovars B and L2 for HeLa 229 cells. Trypsin treatment resulted in a significant loss of attachment and infectivity of serovar B but had no effect on the infectivity of serovar L2. Fluorograms of chlamydiae metabolically labeled with 14C-amino acids and treated with trypsin showed that the major outer membrane protein (MOMP) of both serovars was cleaved. Evidence for two trypsin cleavage sites was found for the serovar B MOMP. One cleavage site was located between lysine 145 and valine 146 in variable domain (VD) II of the protein. The second site was located between lysine 309 and threonine 310 in VD IV. In contrast, the serovar L2 MOMP was cleaved only at lysine 309 in VD IV. These results suggest a functional role for MOMP in chlamydial attachment and implicate VDs II and IV of MOMP in this interaction.
衣原体与宿主细胞的初始相互作用尚未完全明确。在附着过程中起作用的衣原体细胞表面成分是关键毒力因子，对其进行鉴定对于理解这种极为成功的病原体的致病策略至关重要。我们利用胰蛋白酶对衣原体进行蛋白水解，以确定在衣原体与宿主细胞相互作用中起作用的表面成分。我们发现，胰蛋白酶对沙眼衣原体血清型B和L2感染HeLa 229细胞的能力有不同影响。胰蛋白酶处理导致血清型B的附着和感染能力显著丧失，但对血清型L2的感染能力没有影响。用14C-氨基酸进行代谢标记并经胰蛋白酶处理的衣原体的荧光图谱显示，两种血清型的主要外膜蛋白（MOMP）均被切割。在血清型B的MOMP中发现了两个胰蛋白酶切割位点。一个切割位点位于该蛋白可变区（VD）II的赖氨酸145和缬氨酸146之间。第二个位点位于VD IV的赖氨酸309和苏氨酸310之间。相比之下，血清型L2的MOMP仅在VD IV的赖氨酸309处被切割。这些结果表明MOMP在衣原体附着过程中具有功能作用，并表明MOMP的VD II和IV参与了这种相互作用。
