The Myf fibrillae of Yersinia enterocolitica

Abstract

The Myf antigen produced by Yersinia enterocolitica appeared as a proteic polymer composed of 21 kDa subunits. By transposon mutagenesis we isolated Myf-defective mutants. Those allowed us to clone and sequence a 4.4 kb chromosomal locus involved in Myf production. This region was found to contain three genes that we called myfA, myfB and myfC. Genes myfB and myfC encode an assembly machine related to those involved in the synthesis of many fimbriae: MyfB, the putative chaperone, possesses the consensus residues of the PapD family and myfC encodes a putative outer-membrane protein. MyfA, the major subunit, was found to be 44% identical to the pH 6 antigen of Y. pestis. Myf is thus the Y. enterocolitica counterpart of this antigen, but it is by far not so well conserved as the other virulence determinants such as the Yops, suggesting that Myf and pH 6 antigen do not necessarily play the same role in Y. enterocolitica and Y. pestis. The study of the prevalence of myfA in various species of Yersinia revealed that, like the yst enterotoxin gene, its presence is restricted to the pathogenic serotypes of Y. enterocolitica. By immunogold labelling, Myf appeared as a layer of extracellular material extending locally 2 microns from the bacterial surface, indicative of a fibrillar structure.

Structural basis for the specific recognition of dual receptors by the homopolymeric pH 6 antigen (Psa) fimbriae of Yersinia pestis

“…Noticeably, only the bacteria with Psa variants that were impaired in binding to PC were deficient in hemagglutinating activity (Table 1). Bacteria expressing the Psa variant with the corresponding shorter MyfA (W-4X-WY) substitution for the choline-binding motif did not agglutinate RBCs, consistent with the nonhemagglutinating phenotype described for the Myf fimbriae (15). Taken together, our data indicated that the hemagglutinating property of Psa is due to its specificity for cholines on RBCs.…”

“…Only in some studies were a few of these structures visualized as bacterial extensions (15,16) or as linear thin fimbriae (of ∼2-4 nm wide) that are mostly clumped together in small bundles (17,18). However, a structural view at atomic resolution on the subunit PsaA, its assembly into a polyadhesin, and how the two receptors interact with the Psa fimbriae were absent.…”

Transcriptional regulation of the Yersinia pseudotuberculosis pH 6 antigen adhesin by two envelope‐associated components

“…It was initially identified in Yersinia pestis (Aronson and Bichowsky-Slomnicki, 1960) and is physically recognized as a fimbrial structure 3-5 nm in diameter (Lindler and Tall, 1993). The Y. enterocolitica homologue of pH 6 antigen, Myf (mucoid Yersinia factor), forms surface fibrillae as well, but has no known function (Iriarte et al, 1993). In Y. pseudotuberculosis, in addition to mediating haemagglutination, pH 6 antigen is also responsible for thermoinducible adhesion to cultured mammalian cells (Yang et al, 1996).…”

“…Polar transposon insertions in Y. pestis psaE reduce the synthesis of PsaA or eliminate psaA transcription (Lindler et al, 1990;Price et al, 1995). In Y. enterocolitica, transposon insertions in myfE and myfF abolish the synthesis of Myf and eliminate the transcription of myfA (Iriarte et al, 1993;Iriarte and Cornelis, 1995).…”

“…Maximum expression of each occurs during growth at 37ЊC in acidic medium, with little expression seen if the growth temperature is lowered or if the medium is neutralized. Each locus includes a cluster of five genes in the same orientation, called psaEFABC and myfEFABC, respectively (Iriarte et al, 1993;Lindler et al, 1990;Yang et al, 1996). The predicted products of psaABC and myfABC all exhibit a significant degree of similarity to the proteins involved in Escherichia coli pyelonephritis-associated P-pilus biosynthesis Iriarte and Cornelis, 1995;Yang et al, 1996).…”