25IN | pdb_000025in

Mtb galactan transporter Rv3781/3783, open state

• PDB DOI: https://doi.org/10.2210/pdb25IN/pdb
• EM Map EMD-80143: EMDB EMDataResource

• Classification: TRANSPORT PROTEIN
• Organism(s): Mycobacterium tuberculosis H37Rv
• Expression System: Mycolicibacterium smegmatis MC2 155
• Mutation(s): Yes 


• Deposited: 2026-04-06 Released: 2026-10-07 
• Deposition Author(s): Wei, C., Zhang, L.
• Funding Organization(s): National Natural Science Foundation of China (NSFC)

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Experimental Data Snapshot

• Method: ELECTRON MICROSCOPY
• Resolution: 2.91 Å
• Aggregation State: PARTICLE 
• Reconstruction Method: SINGLE PARTICLE 

Literature

Recognition and mechanism of M. tuberculosis cell wall galactan transport.

Wei, C., Abrahams, K.A., Krisilia, V., Li, J., Gurcha, S.S., Derr, E., Hanisch, M., Kalscheuer, R., Besra, G.S., Rao, Z., Zhang, L.

(2026) Nat Commun 17

• PubMed: 42850284 
• DOI: https://doi.org/10.1038/s41467-026-78496-8
• Primary Citation Related Structures: 
  25IN, 25IO, 25IP


• PubMed Abstract: 
  

  Mycobacterial-derived lipid-linked galactan (LLG) is an essential component of the Mycobacterial tuberculosis (Mtb) cell wall core arabinogalactan (AG), a well-established virulence factor and target of anti-tubercular drugs. Cross-membrane translocation of LLG is energetically unfavorable and is therefore catalyzed by WzmWzt, a prominent member of the polysaccharide ABC transporter sub-family. Here we present cryo-EM structures of WzmWzt _Mtb to uncover critical steps of Mtb LLG translocation. Notably, densities suggestive of the mycobacterial-derived LLG substrates were observed in the structure of WzmWzt _Mtb , indicating that the substrate may bind through two Wzm and two Wzt subunits. This proposed LLG binding is fulfilled by a fully upward extension of the Wzt gate helix, which serves as a critical step to prime Wzt for dimerization. The ATP-bound structure revealed a remarkable downward movement of the gate helix, together with the Wzt dimerization. The third, DDM/ATP-bound structure captured WztWzm _Mtb in an intermediate state with two DDM molecules in the Wzm central cavity. Using two conditional mycobacterial mutants for functional analyses, we have identified residues on the Wzm N-terminal interface helix (IF _N ) and on the Wzt helical domain are essential for LLG recognition and translocation in vivo. These data provide a clear structural basis for the development of Mtb cell wall targeted therapeutics for global tuberculosis treatment.

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Organizational Affiliation: 
• Shanghai Institute for Advanced Immunochemical Studies, School of Life Science and Technology, ShanghaiTech University, Shanghai, China.
Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, UK.
Heinrich Heine University Düsseldorf, Faculty of Mathematics and Natural Sciences, Institute of Pharmaceutical Biology and Biotechnology, Düsseldorf, Germany.
Heinrich Heine University Düsseldorf, Faculty of Mathematics and Natural Sciences, Institute of Pharmaceutical Biology and Biotechnology, Düsseldorf, Germany. [e-mail].
Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, UK. [e-mail].
Laboratory of Structural Biology, Tsinghua University, Beijing, China.
Shanghai Institute for Advanced Immunochemical Studies, School of Life Science and Technology, ShanghaiTech University, Shanghai, China. [e-mail].
Shanghai Clinical Research and Trial Center, Shanghai, China. [e-mail].

Biological Assembly 1  

Global Symmetry: Cyclic - C2  (Explore in 3D)
Global Stoichiometry: Hetero 4-mer - A2B2 

Biological assembly 1 assigned by authors.

Biological Assembly Evidence: gel filtration

Macromolecule Content 

• Total Structure Weight: 128.71 kDa 
• Atom Count: 8,584 
• Modeled Residue Count: 1,044 
• Deposited Residue Count: 1,106 
• Unique protein chains: 2

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Probable O-antigen/lipopolysaccharide transport integral membrane protein ABC transporter RfbD	A, B	280	Mycobacterium tuberculosis H37Rv	Mutation(s): 0  Gene Names: rfbD, Rv3783
UniProt
Find proteins for P72049 (Mycobacterium tuberculosis (strain ATCC 25618 / H37Rv)) Explore P72049  Go to UniProtKB:  P72049

Entity ID: 2
Molecule	Chains	Sequence Length	Organism	Details	Image
Probable O-antigen/lipopolysaccharide transport ATP-binding protein ABC transporter RfbE	C, D	273	Mycobacterium tuberculosis H37Rv	Mutation(s): 1  Gene Names: rfbE, Rv3781
UniProt
Find proteins for P72047 (Mycobacterium tuberculosis (strain ATCC 25618 / H37Rv)) Explore P72047  Go to UniProtKB:  P72047

Oligosaccharides

Help  

Entity ID: 3
Molecule	Chains	Length	2D Diagram	Glycosylation	D Interactions
alpha-L-rhamnopyranose-(1-3)-2-acetamido-2-deoxy-1-O-phosphono-alpha-D-glucopyranose	E, F	2	N/A	N/A

Entity ID: 4
Molecule	Chains	Length	2D Diagram	Glycosylation	D Interactions
beta-D-galactofuranose-(1-6)-beta-D-galactofuranose-(1-5)-beta-D-galactofuranose-(1-4)-alpha-L-rhamnopyranose-(1-3)-N-acetyl-beta-D-glucosamine 1-phosphate	G, H	5	N/A	N/A

Small Molecules

Ligands 1 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
A1E8P (Subject of Investigation/LOI)	I [auth A], J [auth A], K [auth B], L [auth B]	[(2~{Z},6~{E})-3,7,11-trimethyldodeca-2,6,10-trienyl] dihydrogen phosphate C15 H27 O4 P ALEWCKXBHSDCCT-PVMFERMNSA-N

Experimental Data & Validation

Experimental Data

• Method: ELECTRON MICROSCOPY
• Resolution: 2.91 Å
• Aggregation State: PARTICLE 
• Reconstruction Method: SINGLE PARTICLE 

EM Software:

Task	Software Package	Version
MODEL REFINEMENT	PHENIX
RECONSTRUCTION	cryoSPARC

Structure Validation

Entry History 

& Funding Information

Deposition Data

• Released Date: 2026-10-07 
Deposition Author(s): Wei, C., Zhang, L.

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Funding Organization	Location	Grant Number
National Natural Science Foundation of China (NSFC)	China	32394011

Revision History  

• Version 1.0: 2026-10-07
  Type: Initial release
  
• Version 1.1: 2026-10-21
  Changes: Data collection, Database references