The psychrotrophic bacterium Yersinia enterocolitica requires expression of pnp, the gene for polynucleotide phosphorylase, for growth at low temperature (5°C)

Abstract

SummaryThe psychrotrophic bacterium Yersinia enterocolitica is characterized by temperature-dependent adaptations. To investigate Y. enterocolitica genes involved in cold adaptation, a mutant restricted in its ability to grow at 5ЊC was isolated from a transposon mutant library. The transposon insertion site in this psychrotrophy-defective (PD) mutant mapped 16 bp upstream of an open reading frame whose predicted amino acid sequence showed 93% similarity with the Escherichia coli exoribonuclease polynucleotide phosphorylase (PNPase), encoded by pnp. Expression of this gene was blocked in the PD mutant. However, the introduction of a second copy of pnp, including 0.33 kbp sequences upstream of its coding region, into the chromosome of the PD mutant restored pnp expression as well as the ability to grow at 5ЊC. Furthermore, the expression of pnp appeared to be temperature dependent: in the parental Y. enterocolitica strain, the levels of both pnp mRNA and PNPase were 1.6-fold higher at 5ЊC compared with 30ЊC. A similarly enhanced level of PNPase at 5ЊC was observed in the merodiploid recombinant strain, which indicates that the 0.33 kbp region upstream of pnp harboured a cold-inducible promoter. A putative cold shock promoter motif (ATTGG) was observed in this region.

Modulation of Yersinia Type Three Secretion System by the S1 Domain of Polynucleotide Phosphorylase

“…This observation prompted us to test whether the phenomenon of PNPase enhancing growth at low temperatures was also independent of its ribonuclease activity, an issue that to the best of our knowledge has not been addressed. Similar to what has been previously reported for E. coli, B. subtilis, and Y. enterocolitica (3)(4)(5), PNPase is clearly required for YPT and YP to grow at low temperatures ( Fig. 9A; data for YP not shown).…”

“…Therefore, although full-length, enzymatically active PNPase is clearly required for optimal growth of Yersinia at low temperature (see below), at higher temperatures it appears to be dispensable for maximal growth in most laboratory conditions. At low temperatures, or in cells recovering from a cold shock, PNPase plays a central role in reprogramming cellular metabolism (4,5,31). Following a cold shock, restart of growth in both E. coli and Y. enterocolitica is preceded by PNPase-mediated degradation of transcripts encoding socalled CSPs (5,31).…”

“…For example, the cold shock response of Escherichia coli involves the induction of several genes including cold shock proteins (CSP) 1 as well as exoribonucleases PNPase and RNaseR involved in RNA metabolism (1,2). In addition to E. coli, Bacillus subtilis and Yersinia enterocolitica have been shown to require PNPase for growth in the cold (3)(4)(5). It is believed that PNPase is required for the restart of growth following cold shock by degrading the remaining CSP mRNA molecules (5,6).…”

Regulation of Escherichia coli Polynucleotide Phosphorylase by ATP

“…In some bacteria such as E. coli and Yersinia enterocolitica, however, it is essential for bacterial growth in the cold (22)(23)(24). PNPase seems also to be directly or indirectly involved in the control of several processes such as cold shock response (25) in E. coli and virulence in Salmonella enterica and Yersinia spp.…”

Enterobacterial common antigen and O-specific polysaccharide coexist in the lipopolysaccharide of Yersinia enterocolitica serotype O : 3

“…Human pathogenic Y. enterocolitica strains belonging most commonly to serotypes O : 3, O : 8 and O : 9 cause diseases, ranging from acute enteritis (especially in children) and enterocolitis to mesenteric lymphadenitis, terminal ileitis and reactive arthritis (Bottone, 1997). Blood contaminated by Y. enterocolitica has caused life-threatening situations after transfusion due to the bacterium's ability to grow at 4 u C (Goverde et al, 1998;Skurnik, 1999).…”