Disease relevance of sarS

• SarA Is a Repressor of hla ({alpha}-Hemolysin) Transcription in Staphylococcus aureus: Its Apparent Role as an Activator of hla in the Prototype Strain NCTC 8325 Depends on Reduced Expression of sarS [1].

High impact information on sarS

• In the agr-independent pathway, MgrA binds directly to hla and the sarS promoter to modulate alpha-hemolysin and protein A expression [2].
• A number of sarA homologs, including sarT and sarS, have been identified in the S. aureus genome [3].
• Transcriptional fusion studies with a 158- and a 491-bp spa promoter fragment linked to the xylE reporter gene disclosed that the transcription of the spa promoter was also downregulated in the sarS mutant compared with the parental strain [4].
• Correlating with this divergent finding is the observation that enhanced sarS expression in an agr mutant was repressed by the sarA locus supplied in trans but not in a sarA mutant expressing RNAIII from a plasmid [4].
• Northern blot analysis revealed much higher levels of sarS mRNA in strain V8 than in 8325-4, which was likely due to the mutation in the sarS activator, tcaR, in 8325-4, which was not found in strain V8 [1].

Biological context of sarS

• Thus, our studies here have defined the nature of interaction of mgrA with other regulators such as agr, sarS, and sarT and its role in regulating hla and spa transcription within the virulence regulatory network of S. aureus [2].
• Northern analysis and transcription fusion assays showed that inactivation of mgrA has led to the downregulation of RNAIII of agr and hla and upregulation of sarS and spa [2].
• The data presented here identified TcaR as a further activator of sarS, and a modulator of sasF expression that has to be taken into account in studies of virulence gene expression in S. aureus [5].
• Regulatory role of proteins binding to the spa (protein A) and sarS (staphylococcal accessory regulator) promoter regions in Staphylococcus aureus NTCC 8325-4 [6].

Regulatory relationships of sarS

• However, the pathway by which the sarA locus downregulates spa expression is sarS independent [4].

Other interactions of sarS

• Interestingly, the enhancement in spa expression in an agr mutant returned to a near-parental level in the agr sarS double mutant but not in the sarA sarS double mutant [4].

Analytical, diagnostic and therapeutic context of sarS

• Expression of sarS and spa in mutants deficient for one, two or three of the identified regulators and in mutants over-expressing selected regulators was analyzed by Northern and Western blotting [6].

References