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

在这项研究中，我们利用一种新开发的宿主-载体系统，包括质粒载体pYH420和限制性缺陷宿主菌株YH522，成功地将牙龈卟啉单胞菌转化为fimA， fimA是菌株381菌菌毛主要亚基蛋白的基因。在该菌株中，引入的fimA基因的表达导致产生的纤维结构在免疫金电镜下与宿主内源性纤维结构有血清学上的区别。从YH522转化体中制备了携带fimA基因的质粒DNA，并将其用于其他牙龈假单胞菌菌株的转化。从6个不同的寄主中获得转化子，并比较了它们的毛状表达以及相对于各自亲本菌株的粘附能力。虽然在这些转化菌中观察到重组菌毛的表达水平有相当大的差异，但很明显，表达高水平重组菌毛的菌株的粘附活性下降得更大。这似乎与有证据表明，宿主内源性纤维蛋白的表达在某种程度上被转化子中重组纤维蛋白基因的表达所抑制有关。

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.