Regulation of saeRS, agrA and sarA on sasX expression in staphylococcus aureus

Abstract

Background: The spread of Staphylococcus aureus and the types of infection caused by S. aureus are closely related to the secretion of a variety of adhesion proteins, which could be controlled by a variety of regulatory systems. However, for the newly discovered adhesion protein SasX, the regulatory mechanism is not completely clear. Objectives: The current study aimed at investigating the regulation of Staphylococcal accessory gene regulator A (agrA), Staphylococcal accessory regulator A (sarA), and two-component signal transduction system (saeRS) on the adhesion protein SasX. Methods: In this research, a saeRS mutant strain, a sarA mutant strain, and a agrA mutant strain were constructed by allelic replacement. In this study mRNA and protein expression levels of sasX in wild-type HS770 and knockout strains were studied to investigate the effects of regulatory factor saeRS, agrA, and sarA on adhesion protein SasX. Results: In contrast with the wild strain HS770, the transcriptional expression of sasX was highest at on the sixth hour time point in HS770∆agrA and at nine and twelve hours in HS770∆sarA. However, the sasX transcription level in HS770∆saeRS mutant strains had little change at different time points. Western-blot results suggested that the sasX expression level of wild strains was the highest at 6 hours; HS770∆saeRS mutation strains had no expression peak at 6 hours. The expression level of HS770∆agrA mutant strains decreased at 6 hours of expression, however, increased at 9 hours and 12 hours; the expression level of HS770∆sarA mutation knockout increased at three, six, nine, and twelve hours. Conclusions: All the results showed that agrA and sarA have negative regulation on sasX, but saeRS may not regulate sasX.