Analysis of gene control of P. gingivalis using a newly developed host-vector system.

在这项研究中，我们证明了使用新开发的针对该物种的宿主载体系统（包括质粒载体pYH420和限制缺陷型宿主菌株YH522），用fimA（来自菌株381的菌毛主要亚基蛋白基因）成功转化牙龈卟啉单胞菌。用该菌株表达导入的fimA基因导致产生纤维状结构，其通过免疫金电子显微镜在血清学上可与宿主的内源性菌毛区分。从YH 522转化体制备携带克隆的fimA基因的质粒DNA，并用于转化其它牙龈卟啉单胞菌菌株。从六种不同的宿主中获得转化体，并比较它们的菌毛表达以及相对于它们各自的亲本菌株的粘附能力。虽然在这些转化体中观察到重组菌毛表达水平的相当大的差异，但显然表达更高水平的重组菌毛的菌株表现出更大的粘附活性降低。这似乎与宿主内源性菌毛蛋白的表达在某种程度上被转化体中的重组fimA基因表达抑制的证据有关。

In this study, we demonstrated the successful transformation of Porphyromonas gingivalis with fimA, the gene for the major subunit protein of the fimbriae from strain 381using a newly developed host-vector system for this species including a plasmid vector pYH420 and a restriction-deficient host strain YH522. With this strain, expression of the introduced fimA gene resulted in production of fibrous structures which were serologically distinguishable from the host's endogenous fimbriae by immunogold electron microscopy.The plasmid DNA carrying the cloned fimA gene was prepared from YH522 transformants and used for transformation of other P. gingivalis strains. Transformants were obtained from six different hosts and compared for their fimbrial expression as well as the capacity for adhesion relative to their respective parental strains. Although a considerable diversity in the expression level of the recombinant fimbriae was observed among those transformants, it was evident that the strains expressing higher levels of the recombinant fimbriae exhibited greater decrease in adhesion activity. This appeared to be related to the evidence that the expression of the host's endogenous fimbrillin was somehow suppressed by recombinant fimA-gene expression in the transformants.