Molecular basis for polysaccharide recognition and modulated ATP hydrolysis by the O antigen ABC transporter

Spellmon, Nicholas; Muszyński, Artur; Górniak, Ireneusz; Vlach, Jiří; Hahn, David K; Azadi, Parastoo; Zimmer, Jochen

doi:10.1038/s41467-022-32597-2

Cited by 8 publications

(4 citation statements)

References 36 publications

(46 reference statements)

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“…The two resolved glycolipid-bound states suggest different ligand-binding sites and/or ATP-independent migration of the substrate within the canyon. Because KpsM is structurally similar to Wzm of the O-antigen ABC transporter, it is possible that KpsMT adopts a similar channel-forming conformation to that of WzmWzt during CPS export 12 , 33 (Fig. 5 and Extended Data Fig.…”

Section: Discussionmentioning

confidence: 99%

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Molecular insights into capsular polysaccharide secretion

Kuklewicz,

Zimmer

2024

Nature

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Capsular polysaccharides (CPSs) fortify the cell boundaries of many commensal and pathogenic bacteria1. 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 subunits1,2. 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.

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Section: Discussionmentioning

confidence: 99%

“…4h). Extending this KpsM movement could create a channel-forming transporter conformation, as observed for the O-antigen WzmWzt transporter 12,32,33 .…”

Section: Glycolipid Binding To the Kpsm Canyonmentioning

confidence: 95%

Molecular insights into capsular polysaccharide secretion

Kuklewicz,

Zimmer

2024

Nature

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“…The last rhamnose residue in this capping unit is O -methylated at the third position. In the E. coli O8 lipopolysaccharide mannan chain, this modification acts as a structural cue for transport across the membrane, thereby terminating polymerisation of the rhamnan chain 45,46 . We therefore propose that a similar mechanism is conserved in Enterococci.…”

Section: Discussionmentioning

confidence: 99%

The Enterococcal Polysaccharide Antigen: from structure to biosynthesis and function

Davis,

Norwood,

Smith

et al. 2024

Preprint

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L-Rhamnose-containing polysaccharides are produced by Streptococci and Enterococci. They define Lancefield serotypes and represent promising candidates for the design of glycoconjugate vaccines. The Enterococcal Polysaccharide Antigen produced by the opportunistic pathogenEnterococcus faecalisplays a critical role in normal growth, division, biofilm formation, antimicrobial resistance, phage susceptibility, and innate immune evasion. Despite the critical role of this polymer forE. faecalisphysiology and host-pathogen interactions, little information is available on its structure and biosynthesis. Here, we elucidate the structure of the intact EPA produced byE. faecalisOG1RF. We report the structure of the linkage unit, revealing an unprecedented complexity of the rhamnose backbone and decorations. Finally, we explore the impact of several EPA structural modifications on innate immune evasion and recognition by bacteriophages. This work represents a first step towards the functional characterisation of EPA for the rational design of therapeutic strategies against a group of important pathogens.

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“…As the CcmAB knockout studies have shown, this does not seem to be indispensable and an arrested CcmCDE complex is still formed 17 , 37 , but this would only require minuscule amounts of heme present in the outer leaflet, which may well be achieved through other pathways or occur spontaneously. Phylogenetically, CcmAB groups with other ABC transporters that act as floppases, with known structures for the O-antigen transporter Wzm-Wzt 41 , and the teichoic acid exporter TarGH 42 . However, we refrain from overstating this analogy, as in the model we present, the cargo would not be transported through the CcmB dimer, but rather along the CcmBC interface.…”

Section: Discussionmentioning

confidence: 99%

Architecture of the Heme-translocating CcmABCD/E complex required for Cytochrome c maturation

Ilcu,

Denkhaus,

Brausemann

et al. 2023

Nat Commun

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Mono- and multiheme cytochromes c are post-translationally matured by the covalent attachment of heme. For this, Escherichia coli employs the most complex type of maturation machineries, the Ccm-system (for cytochrome cmaturation). It consists of two membrane protein complexes, one of which shuttles heme across the membrane to a mobile chaperone that then delivers the cofactor to the second complex, an apoprotein:heme lyase, for covalent attachment. Here we report cryo-electron microscopic structures of the heme translocation complex CcmABCD from E. coli, alone and bound to the heme chaperone CcmE. CcmABCD forms a heterooctameric complex centered around the ABC transporter CcmAB that does not by itself transport heme. Our data suggest that the complex flops a heme group from the inner to the outer leaflet at its CcmBC interfaces, driven by ATP hydrolysis at CcmA. A conserved heme-handling motif (WxWD) at the periplasmic side of CcmC rotates the heme by 90° for covalent attachment to the heme chaperone CcmE that we find interacting exclusively with the CcmB subunit.

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Molecular basis for polysaccharide recognition and modulated ATP hydrolysis by the O antigen ABC transporter

Cited by 8 publications

References 36 publications

Molecular insights into capsular polysaccharide secretion

Molecular insights into capsular polysaccharide secretion

The Enterococcal Polysaccharide Antigen: from structure to biosynthesis and function

Architecture of the Heme-translocating CcmABCD/E complex required for Cytochrome c maturation

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