Expression of the multidrug resistance transporter NorA from Staphylococcus aureus is modified by a two-component regulatory system.
To dissect genetically the regulation of NorA, a multidrug transporter of Staphylococcus aureus, we analyzed the differential expression of the norA promoter using a transcriptional fusion with a beta-lactamase reporter gene. Expression studies with an arlS mutant revealed that the norA promoter is ArlS dependent. The arlR-arlS locus was shown to code for a two-component regulatory system. The protein ArlR has strong similarity to response regulators, and ArlS has strong similarity to protein histidine kinases. We have also analyzed the 350-bp region upstream of the Shine-Dalgarno sequence of norA by gel mobility shift experiments. It was shown that only the 115-bp region upstream of the promoter was necessary for multiple binding of an 18-kDa protein. From transcriptional fusions, we have localized four different putative boxes of 6 bp, which appear to play a role in the binding of the 18-kDa protein and in the up-regulation of norA expression in the presence of the arlS mutation. Furthermore, the gel mobility shift of the 18-kDa protein was modified in the presence of the arlS mutation, and the arlS mutation altered the growth-phase regulation of NorA. These results indicate that expression of norA is modified by a two-component regulatory system.
Fournier
B
B
Infectious Disease Division and Medical Services, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114-2696, USA.
Aras
R
R
Hooper
D C
DC
D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D001483:Base Sequence; D018432:Drug Resistance, Multiple / Q000235:genetics*; D004591:Electrophoresis, Polyacrylamide Gel; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D008970:Molecular Weight; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D013211:Staphylococcus aureus / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins; D027425:ATP-Binding Cassette, Sub-Family C Proteins; C075040:NorA protein, Staphylococcus