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Synergistic computational and experimental studies of a phosphoglycosyl transferase membrane/ligand ensemble.
Majumder, Ayan; Vuksanovic, Nemanja; Ray, Leah C; Bernstein, Hannah M; Allen, Karen N; Imperiali, Barbara; Straub, John E.
Affiliation
  • Majumder A; Department of Chemistry, Boston University, Boston, Massachusetts, USA.
  • Vuksanovic N; Department of Chemistry, Boston University, Boston, Massachusetts, USA.
  • Ray LC; Program in Biomolecular Pharmacology, Boston University School of Medicine, Boston, Massachusetts, USA.
  • Bernstein HM; Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
  • Allen KN; Department of Chemistry, Boston University, Boston, Massachusetts, USA; Program in Biomolecular Pharmacology, Boston University School of Medicine, Boston, Massachusetts, USA. Electronic address: drkallen@bu.edu.
  • Imperiali B; Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA; Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA. Electronic address: imper@mit.edu.
  • Straub JE; Department of Chemistry, Boston University, Boston, Massachusetts, USA. Electronic address: straub@bu.edu.
J Biol Chem ; 299(10): 105194, 2023 10.
Article in En | MEDLINE | ID: mdl-37633332
ABSTRACT
Complex glycans serve essential functions in all living systems. Many of these intricate and byzantine biomolecules are assembled employing biosynthetic pathways wherein the constituent enzymes are membrane-associated. A signature feature of the stepwise assembly processes is the essentiality of unusual linear long-chain polyprenol phosphate-linked substrates of specific isoprene unit geometry, such as undecaprenol phosphate (UndP) in bacteria. How these enzymes and substrates interact within a lipid bilayer needs further investigation. Here, we focus on a small enzyme, PglC from Campylobacter, structurally characterized for the first time in 2018 as a detergent-solubilized construct. PglC is a monotopic phosphoglycosyl transferase that embodies the functional core structure of the entire enzyme superfamily and catalyzes the first membrane-committed step in a glycoprotein assembly pathway. The size of the enzyme is significant as it enables high-level computation and relatively facile, for a membrane protein, experimental analysis. Our ensemble computational and experimental results provided a high-level view of the membrane-embedded PglC/UndP complex. The findings suggested that it is advantageous for the polyprenol phosphate to adopt a conformation in the same leaflet where the monotopic membrane protein resides as opposed to additionally disrupting the opposing leaflet of the bilayer. Further, the analysis showed that electrostatic steering acts as a major driving force contributing to the recognition and binding of both UndP and the soluble nucleotide sugar substrate. Iterative computational and experimental mutagenesis support a specific interaction of UndP with phosphoglycosyl transferase cationic residues and suggest a role for critical conformational transitions in substrate binding and specificity.
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Full text: 1 Collection: 01-internacional Database: MEDLINE Main subject: Transferases / Cell Membrane / Polyprenols Language: En Journal: J Biol Chem Year: 2023 Document type: Article Affiliation country: Estados Unidos

Full text: 1 Collection: 01-internacional Database: MEDLINE Main subject: Transferases / Cell Membrane / Polyprenols Language: En Journal: J Biol Chem Year: 2023 Document type: Article Affiliation country: Estados Unidos