regulation of saers, agra and sara on sasx expression in staphylococcus aureus

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), staphylo- coccal 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 replace- ment. 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 de- creased 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.