Cloning and sequencing of sarA of Staphylococcus aureus, a gene required for the expression of agr.
To evaluate the effect of a sar mutation on the agr locus, Northern (RNA) blotting was performed to determine the levels of RNAIII, the agr regulatory molecule, in two isogenic pairs of Staphylococcus aureus strains. Our results demonstrated that RNAIII was either significantly diminished or absent in both sar mutants compared with the parents. The RNAIII level was partially restored in sar mutants complemented with an intact sar gene (designated sarA). Additionally, we were able to complement selected sar phenotypes with a plasmid carrying RNAIII (pRN6735). These studies suggest that the sarA gene is necessary for the optimal expression of agr. The sarA gene of strain RN450 was subsequently cloned and sequenced. Sequence analysis revealed an open reading frame of 372 bp with a predicted molecular size of 14,718 Da and a deduced pI of 8.52. The deduced protein sequence has a predominance of charged residues (33%) and shares sequence similarity with the virF gene of Shigella flexneri.
Laboratory of Bacterial Pathogenesis and Immunology, Rockefeller University, New York, New York 10021.
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Cheung
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Projan
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics*; D001483:Base Sequence; D015964:Gene Expression Regulation, Bacterial; D006460:Hemolysin Proteins / Q000096:biosynthesis* / Q000235:genetics; D008969:Molecular Sequence Data; D009876:Operon / Q000235:genetics*; D017422:Sequence Analysis, DNA; D013211:Staphylococcus aureus / Q000235:genetics* / Q000472:pathogenicity; D015534:Trans-Activators; D014774:Virulence / Q000235:genetics
D001426:Bacterial Proteins; D006460:Hemolysin Proteins; C088021:SarA protein, bacterial; D015534:Trans-Activators; C025994:delta hemolysin protein, Staphylococcus aureus