Porphyromonas gingivalis, a gram-negative anaerobic bacterium, is associated with the development of periodontal disease. The genetic diversity in virulence factors, such as adhesive fimbriae, among its strains affects the bacterial pathogenicity. P. gingivalis generally expresses two distinct types of fimbriae, FimA and Mfa1. Although the genetic diversity of fimA, encoding the major FimA fimbrilin protein, has been characterized, the genes encoding the Mfa1 fimbrial components, including the Mfa1 to Mfa5 proteins, have not been fully studied. We, therefore, analyzed their genotypes in 12 uncharacterized and 62 known strains of P. gingivalis (74 strains in total). The mfa1 genotype was primarily classified into two genotypes, 53 and 70. Additionally, we found that genotype 70 could be further divided into two subtypes (70A and 70B). The diversity of mfa2 to mfa4 was consistent with the mfa1 genotype, although no subtype in genotype 70 was observed. Protein structure modeling showed high homology between the genotypes in Mfa1 to Mfa4. The mfa5 gene was classified into five genotypes (A to E) independent of other genotypes. Moreover, genotype A was further divided into two subtypes (A1 and A2). Surprisingly, some strains had two mfa5 genes, and the 2nd mfa5 exclusively occurred in genotype E. The Mfa5 protein in all genotypes showed a homologous C-terminal half, including the conserved C-terminal domain recognized by the type IX secretion system. Furthermore, the von Willebrand factor domain at the N-terminal was detected only in genotypes A to C. The mfa1 genotypes partially correlated with the ragA and ragB genotypes (located immediately downstream of the mfa gene cluster) but not with the fimA genotypes.

中文翻译：

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牙龈卟啉单胞菌菌株中编码 Mfa1 菌毛成分的基因的多样性分析。

牙龈卟啉单胞菌是一种革兰氏阴性厌氧菌，与牙周病的发展有关。毒力因子的遗传多样性，如粘菌毛，在其菌株中影响细菌的致病性。P. gingivalis 通常表达两种不同类型的菌毛，FimA 和 Mfa1。尽管编码主要 FimA fimbrilin 蛋白的 fimA 的遗传多样性已被表征，但尚未充分研究编码 Mfa1 菌毛成分（包括 Mfa1 至 Mfa5 蛋白）的基因。因此，我们在 12 个未表征和 62 个已知的牙龈卟啉单胞菌菌株（总共 74 个菌株）中分析了它们的基因型。mfa1 基因型主要分为两个基因型，53 和 70。此外，我们发现基因型 70 可以进一步分为两个亚型（70A 和 70B）。mfa2 到 mfa4 的多样性与 mfa1 基因型一致，尽管在基因型 70 中没有观察到亚型。蛋白质结构模型显示 Mfa1 到 Mfa4 中基因型之间的高度同源性。mfa5 基因被分为五种基因型（A 到 E），独立于其他基因型。此外，基因型A进一步分为两个亚型（A1和A2）。令人惊讶的是，一些菌株具有两个 mfa5 基因，第 2 个 mfa5 仅出现在基因型 E 中。所有基因型中的 Mfa5 蛋白都显示出同源的 C 端一半，包括由 IX 型分泌系统识别的保守 C 端结构域。此外，仅在基因型 A 至 C 中检测到 N 端的 von Willebrand 因子结构域。