Open AccessPolynucleotide phosphorylase independently controls virulence factor expression levels and export in Yersinia spp.
Author(s) -
Rosenzweig Jason A.,
Chromy Brett,
Echeverry Andrea,
Yang Jing,
Adkins Becky,
Plano Gregory V.,
McCutchenMaloney Sandra,
Schesser Kurt
Publication year - 2007
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2007.00689.x
Subject(s) - polynucleotide phosphorylase , biology , yersinia , yersinia enterocolitica , type three secretion system , exoribonuclease , virulence , microbiology and biotechnology , rna , purine nucleoside phosphorylase , gene , genetics , enzyme , biochemistry , bacteria , purine , rnase p
Previously, it was shown that optimal functioning of the Yersinia type III secretion system (T3SS) in cell culture infection assays requires the exoribonuclease polynucleotide phosphorylase (PNPase) and that normal T3SS activity could be restored in the Δ pnp strains by expressing just the ∼70‐aa S1 RNA‐binding domain of PNPase. Here, it is shown that the Yersinia Δ pnp strain is less virulent in the mouse compared with the isogenic wild‐type strain. To begin to understand what could be limiting T3SS activity in the absence of PNPase, T3SS‐encoding transcripts and proteins in the Yersinia Δ pnp strains were analyzed. Surprisingly, it was found that the Δ pnp Yersinia strains possessed enhanced levels of T3SS‐encoding transcripts and proteins compared with the wild‐type strains. We then found that an S1 variant containing a disruption in its RNA‐binding subdomain was inactive in terms of restoring normal T3SS activity. However, T3SS expression levels did not differ between Δ pnp strains expressing active and inactive S1 proteins, further showing that T3SS activity and expression levels, at least as related to PNPase and its S1 domain, are not linked. The results suggest that PNPase affects the expression and activity of the T3SS by distinct mechanisms and that the S1‐dependent effect on T3SS activity involves an RNA intermediate.