Document Detail


Structural and mechanistic studies of HpxO, a novel flavin adenine dinucleotide-dependent urate oxidase from Klebsiella pneumoniae.
MedLine Citation:
PMID:  23259842     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
HpxO is a flavin-dependent urate oxidase that catalyzes the hydroxylation of uric acid to 5-hydroxyisourate and functions in a novel pathway for purine catabolism found in Klebsiella pneumoniae. We have determined the structures of HpxO with and without uric acid at 2.0 and 2.2 Å, respectively. We have also determined the structure of the R204Q variant at 2.0 Å resolution in the absence of uric acid. The variant structure is very similar to that of wild-type HpxO except for the conformation of Arg103, which interacts with FAD in the variant but not in the wild-type structure. Interestingly, the R204Q variant results in the uncoupling of nicotinamide adenine dinucleotide oxidation from uric acid hydroxylation. This suggests that Arg204 facilitates the deprotonation of uric acid, activating it for the oxygen transfer. On the basis of these data, a mechanism for this reaction consisting of a nucleophilic attack of the urate anion on the flavin hydroperoxide resulting in the formation of 5-hydroxyisourate is proposed.
Authors:
Katherine A Hicks; Seán E O'Leary; Tadhg P Begley; Steven E Ealick
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2013-01-09
Journal Detail:
Title:  Biochemistry     Volume:  52     ISSN:  1520-4995     ISO Abbreviation:  Biochemistry     Publication Date:  2013 Jan 
Date Detail:
Created Date:  2013-01-22     Completed Date:  2013-03-14     Revised Date:  2014-01-24    
Medline Journal Info:
Nlm Unique ID:  0370623     Medline TA:  Biochemistry     Country:  United States    
Other Details:
Languages:  eng     Pagination:  477-87     Citation Subset:  IM    
Data Bank Information
Bank Name/Acc. No.:
PDB/3RP6;  3RP7;  3RP8
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MeSH Terms
Descriptor/Qualifier:
Amino Acid Substitution
Bacterial Proteins / chemistry*,  genetics,  metabolism*
Biocatalysis
Catalytic Domain
Crystallography, X-Ray
Flavin-Adenine Dinucleotide / chemistry,  metabolism*
Hydroxylation
Kinetics
Klebsiella pneumoniae / enzymology*
Ligands
Models, Molecular
Molecular Conformation
Mutagenesis, Site-Directed
Mutant Proteins / chemistry,  metabolism
NAD / chemistry,  metabolism
Oxidation-Reduction
Recombinant Proteins / chemistry,  metabolism
Urate Oxidase / chemistry*,  genetics,  metabolism*
Uric Acid / analogs & derivatives,  chemistry,  metabolism
Grant Support
ID/Acronym/Agency:
GM073220/GM/NIGMS NIH HHS; P41 GM103403/GM/NIGMS NIH HHS; P41 RR015301/RR/NCRR NIH HHS; R01 GM073220/GM/NIGMS NIH HHS
Chemical
Reg. No./Substance:
0/5-hydroxyisourate; 0/Bacterial Proteins; 0/Ligands; 0/Mutant Proteins; 0/Recombinant Proteins; 0U46U6E8UK/NAD; 146-14-5/Flavin-Adenine Dinucleotide; 268B43MJ25/Uric Acid; EC 1.7.3.3/Urate Oxidase
Comments/Corrections

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