Molecular insights into the capsular polysaccharide transporter Wza-Wzc complex.
Yuan, B., Sieben, C., Raj, P., Rietschel, T., Hennell James, R., Gatzemeier, A., Jansch, L., Marlovits, T.C., Heinz, D.W.(2026) Nat Commun 17: 1436-1436
- PubMed: 41644548 Search on PubMedSearch on PubMed Central
- DOI: https://doi.org/10.1038/s41467-026-69136-2
- Primary Citation Related Structures: 
9R60, 9R61, 9R62, 9R63, 9R64, 9R65, 9R66, 9R67, 9R68, 9R69, 9R6A, 9R6B, 9R6C - PubMed Abstract: 
Capsular polysaccharides (CPS) are key virulence determinants, constituting the protective capsule that surrounds bacterial pathogens. Here, we present the complete cryo-EM structure of Gram-negative bacterial CPS secretion machinery formed by the E. coli K12 Wza-Wzc complex. The structure reveals an elongated, continuous channel spanning the entire envelope that facilitates CPS secretion. Multiple structural snapshots of the ADP-bound Wza-Wzc complex capture intermediate conformations of the double membrane assembly, highlighting its remarkable intrinsic dynamics. In-depth analysis of the isolated Wza translocon and Wzc co-polymerase, reveals mechanistic details of both complex formation and CPS transport. We further uncover the jellyroll domain of Wzc as a CPS-binding module, likely guiding CPS repeat units into a proposed Wzc-Wzy polymerization platform. Collectively, this work provides structural and functional insights into CPS synthesis and transport, advancing our understanding of bacterial capsule formation and virulence mechanisms.
- Department of Molecular Structural Biology, Helmholtz Centre for Infection Research (HZI), Braunschweig, Germany. biao.yuan@helmholtz-hzi.de.
Organizational Affiliation: 

















