Global analysis of gene expression in an rpoN mutant of Listeria monocytogenes

Abstract

The role of the alternativeσ54factor, encoded by therpoNgene, was investigated inListeria monocytogenesby comparing the global gene expression of the wild-type EGDe strain and anrpoNmutant. Gene expression, using whole-genome macroarrays, and protein content, using two-dimensional gel electrophoresis, were analysed. Seventy-seven genes and nine proteins, whose expression was modulated in therpoNmutant as compared to the wild-type strain, were identified. Most of the modifications were related to carbohydrate metabolism and in particular to pyruvate metabolism. However, under the conditions studied, only themptACDoperon was shown to be directly controlled byσ54. Therefore, the remaining modifications seem to be due to indirect effects. In parallel, anin silicoanalysis suggests thatσ54may directly control the expression of four different phosphotransferase system (PTS) operons, includingmptACD. PTS activity is known to have a direct effect on the pyruvate pool and on catabolite regulation. These results suggest thatσ54is mainly involved in the control of carbohydrate metabolism inL. monocytogenesvia direct regulation of PTS activity, alteration of the pyruvate pool and modulation of carbon catabolite regulation.