Identification of a broad family of lipid A late acyltransferases with non-canonical substrate specificity.

摘要: Summary Most Gram-negative organisms produce lipopolysaccharide (LPS), a complex macromolecule anchored to the bacterial membrane by lipid A moiety. Lipid is synthesized via Raetz pathway, conserved nine-step enzymatic process first characterized in Escherichia coli. The Epsilonproteobacterium Helicobacter pylori uses pathway synthesize A; however, only eight of nine enzymes have been identified this organism. Here, we identify missing acyltransferase, Jhp0255, which transfers secondary acyl chain 3′-linked primary A, an activity similar that E. coli LpxM. This enzyme, reannotated as LpxJ due limited sequence similarity with LpxM, catalyses addition C12:0 or C14:0 complementing E. coli LpxM mutant. Enzymatic assays demonstrate and homologues Campylobacter jejuni Wolinella succinogenes can act before 2′ LpxL, well 3-deoxy-d-manno-octulosonic acid (Kdo) transferase, KdtA. Ultimately, one member large class acyltransferases found diverse range lack homologue, suggesting participates biosynthesis place LpxM homologue.