Given the inhibitory effects of the DksA-dependent regulation of the transcription of amino-acid synthesis and transport , we tested whether the addition of amino-acids had any effect on the marked susceptibility of dksA mutant Salmonella strains to chemically generated NO .
These results indicated that DksA is a positive regulator of genes suggested that invasion phenotypes of the dksA mutant were at least in part due to the lower expression of these genes in the absence of DksA .