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The Myf fibrillae of Yersinia enterocolitica
M Iriarte1, J C Vanooteghem, I Delor
1Microbial Pathogenesis Unit, International Institute of Cellular and Molecular Pathology (ICP), Brussels, Belgium.
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.
Insights
Yersinia enterocolitica produces the Myf antigen, a fibrillar protein layer. Gene analysis identified three genes (myfA, myfB, myfC) responsible for its production and assembly.
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Molecular Biology
Background:
- Yersinia enterocolitica is a significant human pathogen.
- The role of extracellular antigens in Yersinia virulence is an area of ongoing research.
- The Myf antigen's structure and function were previously poorly understood.
Purpose of the Study:
- To characterize the genetic basis of Myf antigen production in Yersinia enterocolitica.
- To elucidate the structure and potential function of the Myf antigen.
- To investigate the prevalence and evolutionary conservation of the myf genes.
Main Methods:
- Transposon mutagenesis to isolate Myf-defective mutants.
- Cloning and sequencing of the chromosomal locus involved in Myf production.
- Bioinformatic analysis of gene sequences and protein homology.
- Immunogold labeling to visualize the Myf antigen's localization and structure.
Main Results:
- A 4.4 kb chromosomal locus containing three genes (myfA, myfB, myfC) was identified as essential for Myf production.
- MyfB and MyfC showed homology to chaperone and outer membrane proteins involved in fimbrial assembly.
- MyfA, the major subunit, shares 44% identity with the Yersinia pestis pH 6 antigen.
- The myfA gene was found predominantly in pathogenic Y. enterocolitica serotypes.
- Immunogold labeling revealed Myf as a fibrillar extracellular layer up to 2 microns thick.
Conclusions:
- The Myf antigen is a fibrillar structure assembled by a machine related to fimbrial synthesis.
- Myf represents the Y. enterocolitica counterpart to the Y. pestis pH 6 antigen, though potentially with different roles.
- The distribution of myfA suggests its importance in the pathogenicity of specific Y. enterocolitica strains.