26GS

Colanic acid polysaccharide related protein structures

Summary for 26GS

• Entry DOI: 10.2210/pdb26gs/pdb
• EMDB information: 80645
• Descriptor: Tyrosine-protein kinase wzc, Putative polysaccharide export protein Wza (2 entities in total)
• Functional Keywords: complex, protein transport
• Biological source: Escherichia coli K-12; More
• Total number of polymer chains: 16
• Total formula weight: 659209.40

Authors

jiao, L.,Yanlong, H. (deposition date: 2026-04-29, release date: 2026-06-24, Last modification date: 2026-07-22)

Primary citation

Liu, J.,Han, Y.,Huang, G.,Zhang, M.,Du, J.,Zhou, H.,Chen, D.,Huang, Y.
Architecture of the Wza-Wzc complex that mediates colanic acid translocation across the cell envelope in Gram-negative bacteria.
Nat Commun, 2026

PubMed Abstract: The Wzx/Wzy-dependent pathway is a highly conserved mechanism for bacterial polysaccharide biosynthesis. This pathway is exemplified by the assembly and export of colanic acid mediated by the Wza-Wzc complex. While recent structural investigations have yielded valuable insights into the molecular basis of colanic acid biosynthesis, the overall architecture of the Wza-Wzc complex and the regulatory mechanism of colanic acid export remain incompletely understood. Here, we report cryo-electron microscopy (cryo-EM) structures of the Wza-Wzc complex from E. coli K12 in two functionally states: the autophosphorylated wild-type (Wza-Wzc) state and the non-phosphorylated (Wza-Wzc) state. Both structures reveal that Wza and Wzc assemble into a continuous channel spanning the entire bacterial cell envelope, indicating that phosphorylation of Wzc does not disassemble the intact export channel. Relative to Wza-Wzc, the octameric periplasmic domain of Wzc in Wza-Wzc undergoes a significant conformational rearrangement. This rearrangement reduces constriction region's diameter and confers a negatively charged property to the interior of the Wzc octamer, which is proposed to inhibit colanic acid export. Collectively, these structural findings confirm that the Wza-Wzc complex forms a colanic acid export channel throughout Wzc's phosphorylation-dephosphorylation cycle, advancing our mechanistic understanding of the Wzx/Wzy-dependent polysaccharide biosynthesis pathway in Gram-negative bacteria.

PubMed: 42399268
DOI: 10.1038/s41467-026-75198-z

Experimental method

ELECTRON MICROSCOPY (3 Å)