DNA microarray analysis of Salmonella typhimurium ptsI mutant strain on virulence gene expression

Abstract

In the enteric bacteria, the mutation of ptsI, encodes enzyme I (EI), has been reported to cause attenuation of virulence in mice. In this study the pathogenic effects of ptsI in Salmonella was investigated through genomic analysis, using S. typhimurium microarray. ptsI mutant exhibited the reduced expression of 200 genes and the induced expression of 225 genes more than two folds under the high-oxygen condition, while 196 genes were increased and 136 genes were decreased in the expression under the low-oxygen condition. Most of SPI-2 genes were reduced in the expression and these might be due to the reduced expression of ompR regulating SsrA-B. The mutation of ptsI also affected chemotaxis/motility. The expression of flgLN required for flagellar biosynthesis, motA as a torque generator, and cheY as a chemotaxis regulator were reduced in the ptsI mutant strain. These results were confirmed in the motility assay, using semi-solid agar. Taken together, the mutation of ptsI changed the expression of many genes, such as pckA, pfkA, nuoALMN, cyoABCD, hycCEG, hydN, aceABK and sdhACD required for the energy production and conversion and the synthesis of vitamin B12