Onoe T, Hoover C I, Nakayama K, Ideka T, Nakamura H, Yoshimura F
Department of Endodontics, School of Dentistry, Aichi-Gakuin University, Nagoya, Japan.
Microb Pathog. 1995 Nov;19(5):351-64. doi: 10.1016/s0882-4010(96)80006-4.
Fimbriae of Porphyromonas gingivalis have been shown to be important as one of the virulence factors for colonization on mucosal surfaces. The gene (fimA) encoding the fimbrial subunit (fimbrilin) was overexpressed in Escherichia coli by using a bacteriophage T7 promoter-polymerase expression vector system. Analysis of the resulting fimA gene product revealed that the prefimbrilin had a 46 amino acid leader peptide. This extremely long leader peptide was cleaved from the prefimbrilin by treatment with trypsin or P. gingivalis extracts containing trypsin-like protease activity, resulting in production of a mature fimbrilin. We also found that some transposon-induced trypsin-like protease deficient mutants of P. gingivalis exhibited deficiency in fimbriation and that one of the mutants accumulated a fimbrilin precursor possessing a 25 amino acid leader peptide in the cell. The presence of an extremely long leader peptide and the requirement for a leader peptidase with a substrate specificity similar to that of P. gingivalis trypsin-like protease for fimbrilin maturation indicate that P. gingivalis fimbrilin is a novel type that is different from fimbrilins of type I and IV families.
牙龈卟啉单胞菌的菌毛已被证明是在粘膜表面定植的毒力因子之一。通过使用噬菌体T7启动子-聚合酶表达载体系统，编码菌毛亚基（菌毛蛋白）的基因（fimA）在大肠杆菌中过表达。对所得fimA基因产物的分析表明，前菌毛蛋白有一个46个氨基酸的前导肽。通过用胰蛋白酶或含有类胰蛋白酶活性的牙龈卟啉单胞菌提取物处理，该极长的前导肽从前菌毛蛋白上被切割下来，从而产生成熟的菌毛蛋白。我们还发现，一些转座子诱导的牙龈卟啉单胞菌类胰蛋白酶缺陷突变体表现出菌毛形成缺陷，并且其中一个突变体在细胞中积累了具有25个氨基酸前导肽的菌毛蛋白前体。极长前导肽的存在以及菌毛蛋白成熟需要一种底物特异性与牙龈卟啉单胞菌类胰蛋白酶相似的前导肽酶，这表明牙龈卟啉单胞菌菌毛蛋白是一种不同于I型和IV型菌毛蛋白家族的新型菌毛蛋白。
