8TT3

S. thermodepolymerans KpsM-KpsE in Glycolipid 2 state with rigid body fitted KpsT

Summary for 8TT3

• Entry DOI: 10.2210/pdb8tt3/pdb
• EMDB information: 41602
• Descriptor: ABC transporter ATP-binding protein, Transport permease protein, Capsular biosynthesis protein, ... (4 entities in total)
• Functional Keywords: abc transporter, capsular polysaccharide, membrane protein
• Biological source: Caldimonas thermodepolymerans; More
• Total number of polymer chains: 12
• Total formula weight: 467326.41

Authors

Kuklewicz, J.,Zimmer, J. (deposition date: 2023-08-12, release date: 2024-04-17, Last modification date: 2024-10-16)

Primary citation

Kuklewicz, J.,Zimmer, J.
Molecular insights into capsular polysaccharide secretion.
Nature, 628:901-909, 2024

PubMed Abstract: Capsular polysaccharides (CPSs) fortify the cell boundaries of many commensal and pathogenic bacteria. Through the ABC-transporter-dependent biosynthesis pathway, CPSs are synthesized intracellularly on a lipid anchor and secreted across the cell envelope by the KpsMT ABC transporter associated with the KpsE and KpsD subunits. Here we use structural and functional studies to uncover crucial steps of CPS secretion in Gram-negative bacteria. We show that KpsMT has broad substrate specificity and is sufficient for the translocation of CPSs across the inner bacterial membrane, and we determine the cell surface organization and localization of CPSs using super-resolution fluorescence microscopy. Cryo-electron microscopy analyses of the KpsMT-KpsE complex in six different states reveal a KpsE-encaged ABC transporter, rigid-body conformational rearrangements of KpsMT during ATP hydrolysis and recognition of a glycolipid inside a membrane-exposed electropositive canyon. In vivo CPS secretion assays underscore the functional importance of canyon-lining basic residues. Combined, our analyses suggest a molecular model of CPS secretion by ABC transporters.

PubMed: 38570679
DOI: 10.1038/s41586-024-07248-9

Experimental method

ELECTRON MICROSCOPY (3.4 Å)