Discovery, characterization, and structural determination of a novel UDP‐2,3‐diacylglucosamine hydrolase

TL;DRAbstract

Gram‐negative bacteria possess an asymmetric outer membrane in which the inner leaflet is composed primarily of phospholipids, while the outer leaflet contains mainly lipopolysaccharide (LPS). LPS forms a structural barrier that protects Gram‐negative bacteria from antibiotics and other environmental stressors. LPS is anchored to the outer membrane by Lipid A, a unique glucosamine‐based saccharolipid. Lipid A biosynthesis is required for viability and pathogenesis. While most lipid A biosynthetic genes are present in a single copy, one gene, lpxH , encoding a membrane‐associated specific UDP‐diacylglucosamine hydrolase, is absent in ~30% of Gram‐negative bacteria. We hypothesized that a transformational analogue of lpxH must exist in these organisms. We identified this gene, designated lpxI , in Caulobacter crescentus , and confirmed its ability to cover for a deficiency of lpxH in Eschserichia coli . LpxI lacks homology to any other known enzyme. We over‐expressed LpxI, purified it, a

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