Polyrhamnose polysaccharide

Polyrhamnose polysaccharide refers to a rhamnose-rich linear polymer (often called rhamnan) that forms a conserved backbone in the cell wall glycopolymers of many Gram-positive bacteria, notably streptococci and lactococci.[2] The backbone commonly consists of repeating →3)α-L-Rha(1→2)α-L-Rha(1→ units, which are variably substituted with species- and serotype-specific side chains such as glucose or N-acetylglucosamine and can be further modified with moieties like glycerol phosphate.[3] This rhamnan core and its decorations (collectively termed Rha-CWPS, SCC in S. mutans, or GAC in S. pyogenes) contribute to cell wall architecture, serotype specificity, and interactions with peptidoglycan via LCP-family enzymes.[2][3] While not a receptor, enzyme, or classical human therapeutic target, the polyrhamnose structure serves as an antigenic scaffold that can be exploited in vaccine design; engineered forms of the Group A carbohydrate lacking GlcNAc side chains have been conjugated to proteins to generate candidate conjugate vaccine antigens.[4]

Other names

Rhamnan[2]Polyrhamnose backbone[2]Rhamnose-rich cell wall polysaccharide (Rha-CWPS)[2]Rhamnopolysaccharide[3]Serotype c-specific carbohydrate (SCC; a polyrhamnose-based polysaccharide of Streptococcus mutans)[3]Group A carbohydrate polyrhamnose (GAC polyrhamnose; GlcNAc-depleted GAC)[4]