2pzj
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(New page: 200px<br /><applet load="2pzj" size="350" color="white" frame="true" align="right" spinBox="true" caption="2pzj, resolution 1.90Å" /> '''Crystal structure of...)
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Revision as of 09:40, 23 January 2008
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Crystal structure of the Bordetella bronchiseptica enzyme WbmF in complex with NAD+
Overview
The pathogenic bacteria Bordetella parapertussis and Bordetella, bronchiseptica express a lipopolysaccharide O antigen containing a polymer, of 2,3-diacetamido-2,3-dideoxy-l-galacturonic acid. The O-antigen cluster, contains three neighbouring genes that encode proteins belonging to the, short-chain dehydrogenase/reductase (SDR) family, wbmF, wbmG and wbmH, and, we aimed to elucidate their individual functions. Mutation and, complementation implicate each gene in O-antigen expression but, as their, putative sugar nucleotide substrates are not currently available, biochemical characterisation of WbmF, WbmG and WbmH is impractical at the, present time. SDR family members catalyse a wide range of chemical, reactions including oxidation, reduction and epimerisation. Because they, typically share low sequence conservation, however, catalytic function, cannot be predicted from sequence analysis alone. In this context, structural characterisation of the native proteins, co-crystals and, small-molecule soaks enables differentiation of the functions of WbmF, WbmG and WbmH. These proteins exhibit typical SDR architecture and, coordinate NAD. In the substrate-binding domain, all three enzymes bind, uridyl nucleotides. WbmG contains a typical SDR catalytic TYK triad, which, is required for oxidoreductase function, but the active site is devoid of, additional acid-base functionality. Similarly, WbmH possesses a TYK triad, but an otherwise feature-poor active site. Consequently, 3,5-epimerase, function can probably be ruled out for these enzymes. The WbmF active site, contains conserved 3,5-epimerase features, namely, a positionally, conserved cysteine (Cys133) and basic side chain (His90 or Asn213), but, lacks the serine/threonine component of the SDR triad and therefore may, not act as an oxidoreductase. The data suggest a pathway for synthesis of, the O-antigen precursor UDP-2,3-diacetamido-2,3-dideoxy-l-galacturonic, acid and illustrate the usefulness of structural data in predicting, protein function.
About this Structure
2PZJ is a Single protein structure of sequence from Bordetella bronchiseptica with as ligand. Full crystallographic information is available from OCA.
Reference
Predicting protein function from structure--the roles of short-chain dehydrogenase/reductase enzymes in Bordetella O-antigen biosynthesis., King JD, Harmer NJ, Preston A, Palmer CM, Rejzek M, Field RA, Blundell TL, Maskell DJ, J Mol Biol. 2007 Nov 30;374(3):749-63. Epub 2007 Sep 26. PMID:17950751
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