Structures of Pseudomonas aeruginosa LpxA Reveal the Basis for Its Substrate Selectivity
- Univ. of South Florida, Tampa, FL (United States)
- ACHAOGEN Inc., South San Francisco, CA (United States)
In Gram-negative bacteria, the first step of lipid A biosynthesis is catalyzed by UDP-N-acetylglucosamine acyltransferase (LpxA) through the transfer of a R-3-hydroxyacyl chain from the acyl carrier protein (ACP) to the 3-hydroxyl group of UDP-GlcNAc. Previous studies suggest that LpxA is a critical determinant of the acyl chain length found in lipid A, which varies among species of bacteria. In Escherichia coli and Leptospira interrogans, LpxA prefers to incorporate longer R-3-hydroxyacyl chains (C14 and C12, respectively), whereas in Pseudomonas aeruginosa, the enzyme is selective for R-3-hydroxydecanoyl, a 10-hydrocarbon long acyl chain. We now report three P. aeruginosa LpxA crystal structures: apo protein, substrate complex with UDP-GlcNAc, and product complex with UDP-3-O-(R-3-hydroxydecanoyl)-GlcNAc. A comparison between the apo form and complexes identifies key residues that position UDP-GlcNAc appropriately for catalysis and supports the role of catalytic His121 in activating the UDP-GlcNAc 3-hydroxyl group for nucleophilic attack during the reaction. Here, the product-complex structure, for the first time, offers structural insights into how Met169 serves to constrain the length of the acyl chain and thus functions as the so-called hydrocarbon ruler. Furthermore, compared with ortholog LpxA structures, the purported oxyanion hole, formed by the backbone amide group of Gly139, displays a different conformation in P. aeruginosa LpxA, which suggests flexibility of this structural feature important for catalysis and the potential need for substrate-induced conformational change in catalysis. Taken together, the three structures provide valuable insights into P. aeruginosa LpxA catalysis and substrate specificity as well as templates for future inhibitor discovery.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- Achaogen Inc.
- OSTI ID:
- 1224477
- Journal Information:
- Biochemistry, Vol. 54, Issue 38; ISSN 0006-2960
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- ENGLISH
Web of Science
Two distinct mechanisms of small molecule inhibition of LpxA acyltransferase essential for lipopolysaccharide biosynthesis
|
posted_content | December 2019 |
| Two distinct mechanisms of small molecule inhibition of LpxA acyltransferase essential for lipopolysaccharide biosynthesis | posted_content | December 2019 |
Substrate specificity of the pyrophosphohydrolase LpxH determines the asymmetry of Bordetella pertussis lipid A
|
journal | March 2019 |
The Inhibition of Lipid A Biosynthesis-The Antidote Against Superbugs?
|
journal | November 2018 |
Discovery of dual-activity small-molecule ligands of Pseudomonas aeruginosa LpxA and LpxD using SPR and X-ray crystallography
|
journal | October 2019 |
Similar Records
Discovery of dual-activity small-molecule ligands of Pseudomonas aeruginosa LpxA and LpxD using SPR and X-ray crystallography
Human N-acetylglucosaminyltransferase II substrate recognition uses a modular architecture that includes a convergent exosite