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Westman, Erin L., Mcnally, David J., Rejzek, Martin, Miller, Wayne L., Kannathasan, Vellupillai Sri, Preston, Andrew, Maskell, Duncan J., Field, Robert A. 
ORCID: https://orcid.org/0000-0001-8574-0275, Brisson, Jean Robert and Lam, Joseph S.
(2007)
Identification and biochemical characterization of two novel UDP-2,3-diacetamido-2,3-dideoxy-α-D-glucuronic acid 2-epimerases from respiratory pathogens.
Biochemical Journal, 405 (1).
pp. 123-130.
ISSN 0264-6021
Abstract
The heteropolymeric O-antigen of the lipopolysaccharide from Pseudomonas aeruginosa serogroup O5 as well as the band-A trisaccharide from Bordetella pertussis contain the di-N-acetylated mannosaminuronic acid derivative, β-D-ManNAc3NAcA (2,3-diacetamido-2,3-dideoxy-β-D-mannuronic acid). The biosynthesis of the precursor for this sugar is proposed to require five steps, through which UDP-α-D-GlcNAc (UDP-N-acetyl-α-D-glucosamine) is converted via four steps into UDP-α-D-GlcNAc3NAcA (UDP-2,3-diacetamido-2, 3-dideoxy-α-D-glucuronic acid), and this intermediate compound is then epimerized by WbpI (P. aeruginosa), or by its orthologue, WlbD (B. pertussis), to form UDP-α-D-ManNAc3NAcA (UDP-2,3-diacetamido-2,3-dideoxy-α-D- mannuronic acid). UDP-α-D-GlcNAc3NAcA, the proposed substrate for WbpI and WlbD, was obtained through chemical synthesis. His6-WbpI and His6-WlbD were overexpressed and then purified by affinity chromatography using FPLC. Capillary electrophoresis was used to analyse reactions with each enzyme, and revealed that both enzymes used UDP-α-D-GlcNAc3NAcA as a substrate, and reacted optimally in sodium phosphate buffer (pH 6.0). Neither enzyme utilized UDP-α-D-GlcNAc, UDP-α-D-GlcNAcA (UDP-2-acetamido-2,3-dideoxy-α-D-glucuronic acid) or UDP-α-D-GlcNAc3NAc (UDP-2,3-diacetamido-2,3-dideoxy-α-D-glucose) as substrates. His6-WbpI or His6-WlbD reactions with UDP-α-D-GlcNAc3NAcA produce a novel peak with an identical retention time, as shown by capillary electrophoresis. To unambiguously characterize the reaction product, enzyme-substrate reactions were allowed to proceed directly in the NMR tube and conversion of substrate into product was monitored over time through the acquisition of a proton spectrum at regular intervals. Data collected from one-and two-dimensional NMR experiments showed that His 6-WbpI catalysed the 2-epimerization of UDP-α-D-GlcNAc3NAcA, converting it into UDP-α-D-ManNAc3NAcA. Collectively, these results provide evidence that WbpI and WlbD are UDP-2,3-diacetamido-2,3-dideoxy-α- D-glucuronic acid 2-epimerases.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | 2-epimerase,lipopolysaccharide,mannosaminuronic acid biosynthesis,o antigen,sugar-nucleotide metabolism,udp-2,3-diacetamido-2,3-dideoxy-α-d- glucuronic acid,biochemistry,molecular biology,cell biology ,/dk/atira/pure/subjectarea/asjc/1300/1303 |
| Faculty \ School: | Faculty of Science > School of Chemistry, Pharmacy and Pharmacology |
| Related URLs: | |
| Depositing User: | LivePure Connector |
| Date Deposited: | 06 Sep 2024 13:35 |
| Last Modified: | 25 Sep 2024 18:07 |
| URI: | https://ueaeprints.uea.ac.uk/id/eprint/96610 |
| DOI: | 10.1042/BJ20070017 |
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