9XGV | pdb_00009xgv

Colanic acid polysaccharide related protein structures

• PDB DOI: https://doi.org/10.2210/pdb9XGV/pdb
• EM Map EMD-66859: EMDB EMDataResource

• Classification: PROTEIN TRANSPORT
• Organism(s): Escherichia coli K-12
• Expression System: Escherichia coli
• Mutation(s): No 


• Deposited: 2025-10-31 Released: 2026-06-24 
• Deposition Author(s): Yihua, H., Yanlong, H.
• Funding Organization(s): Chinese Academy of Sciences

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Experimental Data Snapshot

• Method: ELECTRON MICROSCOPY
• Resolution: 3.25 Å
• Aggregation State: PARTICLE 
• Reconstruction Method: SINGLE PARTICLE 

Literature

Architecture of the Wza-Wzc complex that mediates colanic acid translocation across the cell envelope in Gram-negative bacteria.

Liu, J., Han, Y., Huang, G., Zhang, M., Du, J., Zhou, H., Chen, D., Huang, Y.

(2026) Nat Commun 

• PubMed: 42399268 
• DOI: https://doi.org/10.1038/s41467-026-75198-z
• Primary Citation Related Structures: 
  26GS, 9XGV


• 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 ^WT ) state and the non-phosphorylated (Wza-Wzc ^K540M ) 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 ^K540M , the octameric periplasmic domain of Wzc in Wza-Wzc ^WT 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.

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Organizational Affiliation: 
• State Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.
University of Chinese Academy of Sciences, Beijing, China.
Polyseq Biotechnology Co., Ltd. (Shaoxing), Building 4, Courtyard 6, North Street, Dongsheng Science and Technology Park, Haidian District, Beijing, China.
Institute of Biomedical Research, Yunnan University, Kunming, China.
Institute of Biomedical Research, Yunnan University, Kunming, China. [e-mail].
Southwest United Graduate School, Kunming, China. [e-mail].
State Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China. [e-mail].
University of Chinese Academy of Sciences, Beijing, China. [e-mail].

Biological Assembly 1  

Global Symmetry: Cyclic - C8  (Explore in 3D)
Global Stoichiometry: Hetero 16-mer - A8B8 

Biological assembly 1 assigned by authors.

Biological Assembly Evidence: electron microscopy

Macromolecule Content 

• Total Structure Weight: 973.72 kDa 
• Atom Count: 65,032 
• Modeled Residue Count: 8,392 
• Deposited Residue Count: 8,816 
• Unique protein chains: 2

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Tyrosine-protein kinase wzc	A, B, D, F, H, J, L, N	720	Escherichia coli K-12	Mutation(s): 0  Gene Names: wzc, b2060, JW2045 EC: 2.7.10
UniProt
Find proteins for P76387 (Escherichia coli (strain K12)) Explore P76387  Go to UniProtKB:  P76387

Entity ID: 2
Molecule	Chains	Sequence Length	Organism	Details	Image
Putative polysaccharide export protein Wza	C, E, G, I, K, M, O, P	382	Escherichia coli K-12	Mutation(s): 0  Gene Names: wza, b2062, JW2047
UniProt
Find proteins for P0A930 (Escherichia coli (strain K12)) Explore P0A930  Go to UniProtKB:  P0A930

Experimental Data & Validation

Experimental Data

• Method: ELECTRON MICROSCOPY
• Resolution: 3.25 Å
• Aggregation State: PARTICLE 
• Reconstruction Method: SINGLE PARTICLE 

EM Software:

Task	Software Package	Version
MODEL REFINEMENT	PHENIX	1.20.1_4487
RECONSTRUCTION	cryoSPARC

Structure Validation

Entry History 

& Funding Information

Deposition Data

• Released Date: 2026-06-24 
Deposition Author(s): Yihua, H., Yanlong, H.

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Funding Organization	Location	Grant Number
Chinese Academy of Sciences	China	--

Revision History  

• Version 1.0: 2026-06-24
  Type: Initial release
  
• Version 1.1: 2026-07-22
  Changes: Data collection, Database references