114 research outputs found
Contributions of chaperone/usher systems to cell binding, biofilm formation and Yersinia pestis virulence
Yersinia pestis genome sequencing projects have revealed six intact uncharacterized chaperone/
usher systems with the potential to play roles in plague pathogenesis. We cloned each locus and
expressed them in the Deltafim Escherichia coli strain AAEC185 to test the assembled Y. pestis
surface structures for various activities. Expression of each chaperone/usher locus gave rise to
specific novel fibrillar structures on the surface of E. coli. One locus, y0561-0563, was able to
mediate attachment to human epithelial cells (HEp-2) and human macrophages (THP-1) but not
mouse macrophages (RAW264.7), while several loci were able to facilitate E. coli biofilm
formation. When each chaperone/usher locus was deleted in Y. pestis, only deletion of the
previously described pH 6 antigen (Psa) chaperone/usher system resulted in decreased adhesion
and biofilm formation. Quantitative RT-PCR (qRT-PCR) revealed low expression levels for each
novel chaperone/usher system in vitro as well as in mouse tissues following intravenous infection.
However, a Y. pestis mutant in the chaperone/usher locus y1858-1862 was attenuated for
virulence in mice via the intravenous route of infection, suggesting that expression of this locus is,
at some stage, sufficient to affect the outcome of a plague infection. qRT-PCR experiments also
indicated that expression of the chaperone/usher-dependent capsule locus, caf1, was influenced
by oxygen availability and that the well-described chaperone/usher-dependent pilus, Psa, was
strongly induced in minimal medium even at 28 degrees C rather than 37 degrees C, a temperature previously
believed to be required for Psa expression. These data indicate several potential roles for the
novel chaperone/usher systems of Y. pestis in pathogenesis and infection-related functions such
as cell adhesion and biofilm formation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/91950/1/2011 Microbiology - Contributions of chaperone usher systems to cell binding biofilm formation and Yersinia pestis virulence.pd
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