Crystal Structures of the UDP-diacylglucosamine Pyrophosphohydrase LpxH From Pseudomonas Aeruginosa

Sci Rep. 2016 Sep 9;6:32822. doi: 10.1038/srep32822.

Abstract

Lipid A (also known as endotoxin) is the hydrophobic portion of lipopolysaccharides. It is an essential membrane component required for the viability of gram-negative bacteria. The enzymes involved in its biosynthesis are attractive targets for the development of novel antibiotics. LpxH catalyzes the fourth step of the lipid A biosynthesis pathway and cleaves the pyrophosphate bond of UDP-2,3-diacylglucosamine to yield 2,3-diacylglucosamine 1-phosphate (lipid X) and UMP. Here we present the structures of LpxH from Pseudomonas aeruginosa (PaLpxH). PaLpxH consists of two domains: a catalytic domain that is homologous to the metallophosphoesterases and a helical insertion domain. Lipid X was captured in the crevice between these two domains, with its phosphate group facing the dinuclear metal (Mn(2+)) center and two acyl chains buried in the hydrophobic cavity. The structures reveal that a large conformational change occurs at the lipid X binding site surface upon the binding/release of the product molecule. Based on these observations, we propose a novel model for lipid X embedding, which involves the scissor-like movement of helix α6, resulting in the release of lipid X into the lipid bilayer.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / chemistry
  • Catalytic Domain
  • Crystallography, X-Ray
  • Glycolipids / metabolism*
  • Hydrophobic and Hydrophilic Interactions
  • Lipid A / biosynthesis
  • Models, Molecular
  • Mutation
  • Protein Binding
  • Protein Conformation
  • Pseudomonas aeruginosa / chemistry
  • Pseudomonas aeruginosa / enzymology*
  • Pseudomonas aeruginosa / genetics
  • Pyrophosphatases / chemistry*
  • Pyrophosphatases / genetics
  • Pyrophosphatases / metabolism*

Substances

  • Bacterial Proteins
  • Glycolipids
  • Lipid A
  • lipid X
  • Pyrophosphatases
  • UDP-2,3-diacylglucosamine pyrophosphatase