Elucidation of Mechanisms in Fimbrial Morphogenesis in Periodontopathogens

1.牙龈卟啉单胞菌中的菌毛似乎携带三种不同类型的菌毛，分别由40 kDa的FimA、75 kDa的MFA和53 kDa的蛋白质组成。2.牙龈卟啉单胞菌W83菌株中这三种菌毛的分布似乎都没有。虽然它有FIMA(基因IV)基因，但它似乎不表达FIMA菌毛。因为MFA基因在染色体上被破坏，所以它不会产生MFA菌毛。ATCC 33277菌株产生两种菌毛，FimA和MfA。3FIMA菌毛的变异目前已报道的有6种FIMA基因。我们已经从基因I、Ib和II菌株中提纯了菌毛。它们有大量的菌毛可供净化。4.不同FIMA基因菌株菌毛的提取方法不同，只需用温和的缓冲液对细菌细胞进行简单的洗涤，即可有选择性地提取基因I型菌毛。而Ib和Ii的其他基因型菌毛不能通过这样的洗涤提取。它们可以通过法国出版社的细胞破碎来溶解。这些结果可能意味着它们具有非常不同长度的纤维。基因I的菌毛很长，但其他类型的菌毛太短而不能从细胞表面剥离，这一假设可以得到验证。5.菌毛形态发生的调节fimxy基因似乎在菌毛形态发生过程中对FIMA蛋白的表达起着重要作用。FimR基因的产物是一个正调节因子，被发现与fimxy上游的区域结合，以产生菌毛蛋白。

1.Fimbriae in Porphyromonas gingivalis, a periodontopathogenP.gingivalis seems to carry three different types of fimbriae which are composed of 40-kDa FimA,75-kDa Mfa, and 53-kDa protein, respectively, as a major subunit.2.Distribution of the three fimbriae in P.gingivalisStrain W83 seems to carry none of them. Although it has the fimA (genotype IV) gene, it does not seem to express FimA fimbriae. Because the mfa gene is disrupted in the chromosome, it does not produce Mfa fimbriae. Two fimbriae, FimA and Mfa, are produced in strain ATCC 33277. Some of the P.gingivalis strains including 381 appear to have the three fimbriae.3.Variation of fimA fimbriaeThere are six genotypes in the fimA gene, thus far reported. We have purified fimbriae from genotype I,Ib, and II strains. They have a plenty of fimbriae for purification. However, we do not know whether all the genotype strains carry a plenty of fimbraie on the cell surface.4.Different extraction methods for fimbriae from strains with different fimA genotypesGenotype I fimbraie can be selectively extracted by a simple washing of bacterial cells with a mild buffer. However, other genotype fimbraie of Ib and II could not be extracted by such washing. They can be solubilized through the cell breakage by a French Press. These results might imply that they have fibers with very different lengths. This assumption that genotype I fimbriae are long, but other genotypes of fimbraie are too short to be sheared off from the cell surfaces could be verified.5.Regulation in fimbrial morphogenesisThe genes of fimXY appear to play an important role in expression of fimA protein in fimbrial morphogenesis. The product of the fimR gene, a positive regulator, is discovered to bind to the region upstream from fimXY for production of the fimbrial protein.