Revisiting the regulation of the capsular polysaccharide biosynthesis gene cluster in Staphylococcus aureus

What is it about?

The majority of bacterial pathogens produce an array of polysaccharides on their surface which are important virulence factors and serve as attractive vaccine candidates. However, the synthesis and assembly of these structures is highly variable and tightly regulated at various levels. In the human pathogen Staphylococcus aureus, the synthesis of the capsular polysaccharide (CP) is dependent on a complex regulatory network which ensures that CP is produced only in a fraction of stationary phase cells. Here, we determined main regulators that drive the peculiar CP expression pattern. We found that the interplay of repressors targeting an upstream promoter region with activity of the alternative Sigma factor B is responsible for early-Off/late-Heterogeneous expression at the transcriptional level. The data also implicates post-transcriptional mechanisms that may act to avoid conflict in precursor usage by machineries involved in either synthesis of CP or other glycopolymers in growing bacterial cells.

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