Effect of RsaA on capsule formation.

<p>(A) Dot-blot analysis of capsular polysaccharide accumulation in wild-type strains and its corresponding Δ<i>rsa</i>A mutant and complemented strains after growth in BHI for 16 h. Standardized bacterial suspensions were treated with lysostaphine, DNase I and proteinase K, and 1/3 serial dilutions were spotted onto nitrocellulose membranes. Capsular polysaccharides were detected with an anti-CP5 (HG001 and Newman) or CP8 (Becker) antisera. The Δ<i>rsa</i>A mutant produced a higher level of capsular polysaccharides and the Δ<i>mgr</i>A mutant produced a lower level of capsular polysaccharides. The inactivation of both <i>rsa</i>A and <i>mgr</i>A revealed that the repression of capsule production by <i>rsa</i>A achieved via the repression of <i>mgr</i>A. (B) Capsule production in Becker strain and its derivatives grown for 7 h in BHI at 37°C. CP8 expression was determined by indirect immunofluorescence of WT strain, the Δ<i>rsa</i>A mutant strain (LUG2010) and the mutant strain complemented with a plasmid expressing RsaA (LUG2032). The bacteria were labeled with Bodipy-vancomycine and capsule was labeled with an anti-CP8 antibody and a rabbit anti-IgG coupled with a fluorochrome AlexaFluor 647.