Fig. 1: Wzc and the Wzx-Wzy pathway.
From: Molecular basis for the phosphorylation of bacterial tyrosine kinase Wzc
a Schematic model for the assembly and export of capsular polysaccharide (CPS) in E. coli K30, the prototype for Wzy-dependent CPS biogenesis. The repeat unit of E.coli K30 CPS50 is synthesized on an undecaprenol diphosphate carrier lipid at the cytoplasmic side of the inner membrane (IM) by a phosphoglycosyltransferase (PGT; WbaP) and glycosyltransferases (GT(s); WbaZ, WcaO and WcaN), and flipped to the periplasmic face of the membrane by Wzx. The repeat units are polymerized by Wzy, and the polymers are exported by Wza1. Polymerization and export are regulated by Wzc (a PCP-2a family autokinase), which cycles between a phosphorylated state and dephosphorylated state due the activity of the Wzb phosphatase9. Wzi is involved in the surface attachment of CPS1. b The gene cluster for the synthesis and export of the CPS of E. coli K30 (GenBank Acc. AF104912.3). c A cartoon of a Wzc monomer, comprising the periplasmic domain containing motif 1–3, two transmembrane helices, the BY-kinase domain, and the C-terminal tyrosine-rich tail (Y-tail) (adapted from9).
