8e37

Publication Abstract from PubMed

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 (PGT) 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 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 undecaprenol phosphate with PGT cationic residues and suggest a role for critical conformational transitions in substrate binding and specificity.

Synergistic computational and experimental studies of a phosphoglycosyl transferase membrane/ligand ensemble.,Majumder A, Vuksanovic N, Ray LC, Bernstein HM, Allen KN, Imperiali B, Straub JE J Biol Chem. 2023 Aug 24:105194. doi: 10.1016/j.jbc.2023.105194. PMID:37633332^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.