Crystal structures of the UDP-diacylglucosamine pyrophosphohydrase LpxH from Pseudomonas aeruginosa.
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.
Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan.
Chiaki
C
Okada
Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan.
Hiroko
H
Wakabayashi
Graduate School of Life Science, Hokkaido University, Sapporo 060-0810, Japan.
Momoko
M
Kobayashi
Graduate School of Life Science, Hokkaido University, Sapporo 060-0810, Japan.
Akira
A
Shinoda
Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan.
Isao
I
Tanaka
Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan.|Graduate School of Life Science, Hokkaido University, Sapporo 060-0810, Japan.|Department of Pharmacology, Basic Medical College of Zhengzhou University, Zhengzhou, China.
Min
M
Yao
D001426:Bacterial Proteins / Q000737:chemistry; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D006017:Glycolipids / Q000378:metabolism*; D057927:Hydrophobic and Hydrophilic Interactions; D008050:Lipid A / Q000096:biosynthesis; D008958:Models, Molecular; D009154:Mutation; D011485:Protein Binding; D011487:Protein Conformation; D011550:Pseudomonas aeruginosa / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D011755:Pyrophosphatases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins; D006017:Glycolipids; D008050:Lipid A; C044283:lipid X; D011755:Pyrophosphatases; C464799:UDP-2,3-diacylglucosamine pyrophosphatase