The insecticidal toxin genes of Yersinia enterocolitica are activated by the thermolabile LTTR‐like regulator TcaR2 at low temperatures. Issue 4 (16th July 2013)

• Record Type: Journal Article
• Authors: Starke, Mandy; Richter, Marleen; Fuchs, Thilo M.
• Is Part Of: Molecular microbiology. Volume 89:Issue 4(2013)
• Page Start: 596
• Page End: 611
• Publication Date: 2013-07-16
• Subjects: Molecular microbiology -- Periodicals; 572.829
• DOI: 10.1111/mmi.12296
• Languages: English
• ISSNs: 0950-382X

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>Temperature‐dependent activation of bacterial virulence factors at 37°C is well investigated. The molecular mechanism underlying the expression of toxicity determinants at environmental temperatures, however, has not been characterized. The insecticidal activity of <italic>Yersinia enterocolitica</italic> strain W22703 requires the toxin complex subunit A (TcaA) encoded on the pathogenicity island Tc‐PAI<italic><sub>Ye</sub></italic>. Genes <italic>tcaA</italic> and <italic>tcaB</italic> encoding this subunit are maximally produced at low temperatures (10–20°C), but repressed at body temperature. Two further insecticidal genes, <italic>tcaC</italic> (subunit B) and <italic>tccC1</italic> (subunit C), are silent at both temperatures. A novel LysR‐type transcriptional regulator (LTTR), TcaR2, revealed to be autoregulated and essential for <italic>tcaA</italic> and <italic>tcaB</italic> expression in W22703. Expression of <italic>tcaR2</italic> is negatively controlled by a second LTTR‐like regulator, TcaR1. Gel mobility shift assays confirmed the interaction of TcaR2 with the <italic>tcaR2</italic>, <italic>tcaA</italic> and <italic>tcaB</italic> promoters. The activity of the <italic>tcaA</italic> promoter in heterologous hosts in the presence of TcaR2 excludes the requirement of additional, <italic>Yersinia</italic>‐specific (co)factors for toxin gene expression. Overproduced TcaR2 protein is shown to be unstable at 37°C, whereas the mRNA of <italic>tcaA</italic> and <italic>tcaR2</italic> is equally stable at low and high temperature. Thus, TcaR2 is a key player in the induction of insecticidal genes in <italic>Y. enterocolitica</italic> at low temperatures.</p> </abstract>