Anchoring and length regulation of Porphyromonas gingivalis Mfa1 fimbriae by the downstream gene product Mfa2

Abstract

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.

E-Selectin Mediates Porphyromonas gingivalis Adherence to Human Endothelial Cells

“…P. gingivalis ATCC 33277 was used as a wild-type strain in this study. P. gingivalis defective mutants lacking fimA were constructed as described previously (17). A P. gingivalis Pgm6/7-deficient mutant was constructed as described previously (32).…”

Characterization of Wheat Germ Agglutinin Lectin-Reactive Glycosylated OmpA-Like Proteins Derived from Porphyromonas gingivalis

“…Protein analysis by MS. Isolated proteins were identified by matrixassisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) as described previously (30,31). CBB-or SyproRubystained protein bands were excised from the SDS-PAGE gels and digested with trypsin.…”

Genetic exchange and reassignment in Porphyromonas gingivalis

“…However, strains with fimA genotypes III and V express 53K fimbriae almost exclusively, while fimA genotypes I and II tend to express Mfa 1 fimbriae. The downstream gene product Mfa 2 has a role as anchor for the Mfa 1 fimbriae and as regulator of the Mfa 1 filament length [23]. It is likely that the distinct short fimbria-molecules found in different strains as well as long fimbriae both influence initiation and progression of periodontal disease [24].…”