MOLECULAR BIOLOGICAL STUDIES ON ADHERENT FACTORS OF A PERIODONTOPATHOGEN

牙龈卟啉单胞菌是一种革兰氏阴性的口腔厌氧菌，被认为是一种牙周病病原体。它有几个粘附因子，如菌毛、血凝素和外膜蛋白可能是致毒因子。对fimA基因编码纤原蛋白的下游区域进行了测序，在该区域发现了4个开放阅读框（orf）。ORF2和ORF3分别编码50- kda和80-kDa蛋白，作为次要组分参与菌毛。利用自杀载体进行插入诱变，获得了ORF3突变体。该突变体在细胞内产生纤原蛋白，但在细胞表面没有纤原。具有胰蛋白酶样蛋白酶活性（HA/P）的血凝素也被研究过。编码这种独特物质的基因被克隆并几乎完全测序。DNA序列显示HA/P是从一个大的ORF中表达的，血凝素和蛋白酶结构域似乎位于n端区域。它们似乎共享一个共同的活性位点。此外，还克隆了一个主要外膜蛋白（75-kDa）的编码基因，并对其进行了测序。

Porphyromonas gingivalis is a Gram-negative, oral anaerobe and has been considered to be a periodontopathogen. It has several adherent factors such as fimbriae, hemagglutinin, and an outer membrane protein as possible virulent factors. Region downstream from the fimA gene encoding fimbrilin, a major subunit of fimbriae, was seqenced, and four open reading frames (ORFs) were found in this region. ORF2 and ORF3 encoding 50- and 80-kDa protein, respectively, were found to be involved in fimbriae as minor components. A mutant possessing mutation in ORF3 was created by insertional mutagenesis using a suicide vector. This mutant produced fimbrilin in cell, but no fimbriae on the surface of the cell. Hemagglutinin possessing trypsin-like protease activity (HA/P) has also been studied. Gene encoding this unique substance was cloned and sequenced almost completely. The DNA sequence revealed that HA/P is expressed from a large ORF and the hemagglutinin and protease domains seem to be located in the N-terminal region. They seem to share one common active site. Gene encoding a major outer membrane protein (75-kDa) was also cloned and sequenced.