Chen W, Kuramitsu H K
Department of Oral Biology, State University of New York, Buffalo, New York 14214, USA.
Infect Immun. 1999 Sep;67(9):4926-30. doi: 10.1128/IAI.67.9.4926-4930.1999.
Porphyromonas gingivalis is one of the pathogens associated with periodontal diseases, and its protease activity has been implicated as an important virulence factor. Kgp is the major Lys-gingipain protease of P. gingivalis and appears to be involved not only in enzyme activity but also in hemagglutination and the pigmented phenotype due to heme accumulation and/or hemoglobin binding. However, little information concerning the molecular mechanism for the spontaneous generation of pigmentless P. gingivalis mutants is currently available. In this study, several spontaneous pigmentless mutants of P. gingivalis were isolated and characterized. The results revealed that a portion of the kgp gene had been deleted from the chromosomes of the pigmentless mutants. This deletion appears to result from recombination between the highly homologous DNA sequences encoding the adhesin domains of the tandemly arranged hagA and kgp genes on the chromosomes of P. gingivalis strains.
牙龈卟啉单胞菌是与牙周疾病相关的病原体之一，其蛋白酶活性被认为是一种重要的毒力因子。Kgp是牙龈卟啉单胞菌主要的赖氨酸牙龈蛋白酶，似乎不仅参与酶活性，还参与血细胞凝集以及由于血红素积累和/或血红蛋白结合导致的色素沉着表型。然而，目前关于无色素牙龈卟啉单胞菌突变体自发产生的分子机制的信息很少。在本研究中，分离并鉴定了几种牙龈卟啉单胞菌的自发无色素突变体。结果显示，无色素突变体的染色体上kgp基因的一部分已被删除。这种缺失似乎是由于牙龈卟啉单胞菌菌株染色体上串联排列的hagA和kgp基因的粘附素结构域编码的高度同源DNA序列之间的重组所致。
