Wzc

Wzc is a gene encoding a bacterial tyrosine autokinase that is a component of the capsule polysaccharide (CPS) export system in many Gram-negative bacteria. It is commonly found within operons responsible for the synthesis and export of extracellular polysaccharides, such as the wza–wzb–wzc cluster. In this context, Wzc functions together with the periplasmic phosphatase Wzb and the outer membrane channel Wza to regulate the assembly and surface export of capsule material, which forms a protective extracellular layer and contributes to virulence and biofilm formation.

Structure and mechanism: Wzc proteins typically comprise an N-terminal membrane-anchoring region, a cytoplasmic tyrosine kinase domain that autophosphorylates on tyrosine residues, and often a periplasmic domain. Autokinase activity is regulated by phosphorylation state, with Wzb catalyzing dephosphorylation. The kinase activity is ATP-dependent and is thought to coordinate polysaccharide chain elongation with export, thereby influencing polymer length and efficiency of capsule export.

Biological role and significance: Capsule production enhances resistance to phagocytosis and environmental stresses, and affects adhesion and immune evasion. Variation in Wzc activity or expression can alter capsule amount and composition, influencing virulence, host interaction, and biofilm formation.

Genetics and distribution: The wzc gene is found in diverse Gram-negative genera, including Escherichia, Klebsiella, and Salmonella, typically as part of capsule loci. Mutations in wzc can disrupt capsule export, while changes in expression can modulate capsule production.

See also: Wza, Wzb, capsule, capsular polysaccharide export system.