YmoA negatively controls the expression of insecticidal genes in Yersinia enterocolitica

Abstract

SummaryYersinia enterocolitica is toxic towards invertebrates due to the presence of the toxin complex (tc) genes that are activated by the thermolabile regulator TcaR2. In the search for further regulatory factors involved in insecticidal gene expression, the modulator of yersinial virulence, YmoA, was identified to silence all tc genes of the Y. enterocolitica strain W22703 (biovar 2, serovar O:9). Using promoter fusions with the luciferase reporter, we found that the deletion of ymoA results in elevated transcription of tcaR1, tcaR2, tcaA, tcaB, tcaC, tccC1 and tccC2 at both 15°C and 37°C. Complementation by episomal ymoA significantly reduced tc gene expression, thus validating the inhibitory activity of YmoA on the production of insecticidal proteins. YmoA contributes to the binding properties of H-NS to the tc promoters by forming a complex with this nucleoid-associated protein, and this complex not only binds to the upstream regions of all tc genes, but also to intragenic sites of tcaA and tcaB that play an important role in controlling the expression of both genes. At low temperature, the intracellular amount of thermostable YmoA is not reduced, but the repressor is less functional. These data point to H-NS/YmoA as an antagonist of the inducer TcaR2.

WITHDRAWN: The Impact of ymoA Gene Expression on Enterotoxin YstA Production by Yersinia Enterocolitica Strains With Different Enterotoxic Properties

“…According to our knowledge, this study is the second research attempt to investigate the in uence of YmoA on the production of enterotoxins by Y. enterocolitica. The other study was conducted by Starke and Fuchs 25 who demonstrated that YmoA silenced all tc genes of Y. enterocolitica strain W22703 (biotype 2, serotype O:9). Using fusions of promoter with the luciferase reporter, they detected that the deletion of ymoA increased the transcription of tcaR1, tcaR2, tcaA, tcaB, tcaC, tccC1 and tccC2 at 15°C and 37°C temperatures.…”

“…In 1998, Grant et al 24 have also suggested that the lack of enterotoxic properties in selected Y. enterocolitica strains could result from the inhibitory in uence of the ymoA gene on ystA gene expression in in vitro cultures. To date, this possibility has been investigated only by Starke and Fuchs 25 who identi ed YmoA as a silencing factor for all toxic complex (tc) genes of Y. enterocolitica strain W22703 (biotype 2, serotype O:9).…”

High binding affinity of repressor IolR avoids costs of untimely induction of myo-inositol utilization by Salmonella Typhimurium

“…3). The molecular excess of protein over DNA for quantitative binding of most promoters tested was in a range between 5 to 21 and thus very low in comparison with other repressors tested under similar conditions1112, pointing to a strong affinity of IolR to its target sequences. The bandshift experiments with the promoters P iolT1 , P iolD1 , P iolR , P iolC1 and P reiD exhibited at least two retarded protein/DNA complexes, suggesting an oligomerization of IolR with increasing protein concentration.…”

Thermal control of virulence factors in bacteria: A hot topic

“…We focus on examples of how microbes sense the elevated temperatures once they enter a mammalian host, even though pathogens of plants and insects can regulate gene expression in response to lower temperatures. [2][3][4] Mechanisms of thermo-sensing: exerting multi-level control Regulation at the level of DNA Changes in the local temperature are detected by bacteria through multiple mechanisms; temperature can influence the topology of DNA, affect RNA structuring and metabolism, and change the activity and processing of proteins ( Fig. 2).…”