3oa2
From Proteopedia
Crystal structure of the WlbA (WbpB) dehydrogenase from Pseudomonas aeruginosa in complex with NAD at 1.5 angstrom resolution
Structural highlights
Function[WBPB_PSEAE] Plays a role in the biosynthesis of B-band O antigen for serotype O5. Catalyzes the NAD-dependent oxidation of UDP-N-acetylglucosaminuronic acid (UDP-D-GlcNAcA) to UDP-2-acetamido-2-deoxy-3-oxo-D-glucuronic acid (UDP-3-oxo-D-GlcNAcA). Can not use UDP-GlcNAc or UDP-GalNAc as the nucleotide sugar substrate, and can use only poorly UDP-D-glucuronic acid (UDP-GlcA). Undergoes an NAD(+) recycling mechanism using 2-oxoglutarate as an oxidant.[1] [2] [3] [4] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed2,3-Diacetamido-2,3-dideoxy-d-mannuronic acid (ManNAc3NAcA) is an unusual dideoxy sugar first identified nearly 30 years ago in the lipopolysaccharide of Pseudomonas aeruginosa O:3a,d. It has since been observed in other organisms, including Bordetella pertussis, the causative agent of whooping cough. Five enzymes are required for the biosynthesis of UDP-ManNAc3NAcA starting from UDP-N-acetyl-d-glucosamine. Here we describe a structural study of WlbA, the NAD-dependent dehydrogenase that catalyzes the second step in the pathway, namely, the oxidation of the C-3' hydroxyl group on the UDP-linked sugar to a keto moiety and the reduction of NAD(+) to NADH. This enzyme has been shown to use alpha-ketoglutarate as an oxidant to regenerate the oxidized dinucleotide. For this investigation, three different crystal structures were determined: the enzyme with bound NAD(H), the enzyme in a complex with NAD(H) and alpha-ketoglutarate, and the enzyme in a complex with NAD(H) and its substrate (UDP-N-acetyl-d-glucosaminuronic acid). The tetrameric enzyme assumes an unusual quaternary structure with the dinucleotides positioned quite closely to one another. Both alpha-ketoglutarate and the UDP-linked sugar bind in the WlbA active site with their carbon atoms (C-2 and C-3', respectively) abutting the re face of the cofactor. They are positioned approximately 3 A from the nicotinamide C-4. The UDP-linked sugar substrate adopts a highly unusual curved conformation when bound in the WlbA active site cleft. Lys 101 and His 185 most likely play key roles in catalysis. Structural and Functional Studies of WlbA: A Dehydrogenase Involved in the Biosynthesis of 2,3-Diacetamido-2,3-dideoxy-d-mannuronic Acid .,Thoden JB, Holden HM Biochemistry. 2010 Aug 19. PMID:20690587[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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