Anchoring and length regulation of Porphyromonas gingivalis Mfa1 fimbriae by the downstream gene product Mfa2
Anchoring and length regulation of Porphyromonas gingivalis Mfa1 fimbriae by the downstream gene product Mfa2
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DOI：
10.1099/mic.0.028928-0
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发表时间：
2009-10-01
期刊：
影响因子：
2.8
通讯作者：
Yoshimura, Fuminobu
中科院分区：
文献类型：
--
作者：
Hasegawa, Yoshiaki;Iwami, Jun;Yoshimura, Fuminobu
牙龈卟啉单胞菌（Porphyromonas gingivalis）是牙周炎的病原体，具有至少两种类型的薄的单链菌毛，称为FimA和Mfa1（根据主要亚基的名称），其可以通过细丝长度和其主要菌毛蛋白亚基的大小来区分。FimA菌毛是很容易从细胞上脱落的长丝状体，而Mfa1菌毛是紧密结合在细胞上的短丝状体。然而，牙龈卟啉单胞菌ATCC 33277衍生的mfa2（mfa1的下游基因）缺陷突变体产生长丝状体（比亲本长10倍），容易从细胞表面分离，类似于FimA菌毛。较长的Mfa1菌毛有助于细菌细胞更强的自聚集。突变体与野生型mfa2等位基因反式互补恢复了亲本表型。Mfa2存在于牙龈卟啉单胞菌的外膜中，但不与Mfa1菌毛共纯化。然而，免疫共沉淀表明，Mfa2和Mfa1在整个牙龈卟啉单胞菌细胞中相互关联。此外，免疫金显微镜，包括双标记，证实Mfa2位于细胞表面，并可能与Mfa1菌毛。因此，Mfa 2可能作为Mfa 1菌毛的锚发挥作用，也作为Mfa 1细丝长度的调节剂。另外两个下游基因（pgn0289和pgn0290）与mfa1（pgn0287）和mfa2（pgn0288）共转录，并且来自pgn0289、pgn0290和pgn0291的蛋白质似乎是辅助菌毛组分。
Porphyromonas gingivalis, a causative agent of periodontitis, has at least two types of thin, single-stranded fimbriae, termed FimA and Mfa1 (according to the names of major subunits), which can be discriminated by filament length and by the size of their major fimbrilin subunits. FimA fimbriae are long filaments that are easily detached from cells, whereas Mfa1 fimbriae are short filaments that are tightly bound to cells. However, a P. gingivalis ATCC 33277-derived mutant deficient in mfa2, a gene downstream of mfa1, produced long filaments (10 times longer than those of the parent), easily detached from the cell surface, similar to FimA fimbriae. Longer Mfa1 fimbriae contributed to stronger autoaggregation of bacterial cells. Complementation of the mutant with the wild-type mfa2 allele in trans restored the parental phenotype. Mfa2 is present in the outer membrane of P. gingivalis, but does not co-purify with the Mfa1 fimbriae. However, co-immunoprecipitation demonstrated that Mfa2 and Mfa1 are associated with each other in whole P. gingivalis cells. Furthermore, immunogold microscopy, including double labelling, confirmed that Mfa2 was located on the cell surface and likely associated with Mfa1 fimbriae. Mfa2 may therefore play a role as an anchor for the Mfa1 fimbriae and also as a regulator of Mfa1 filament length. Two additional downstream genes (pgn0289 and pgn0290) are co-transcribed with mfa1 (pgn0287) and mfa2 (pgn0288), and proteins derived from pgn0289, pgn0290 and pgn0291 appear to be accessory fimbrial components.