3RP6

Crystal Structure of Klebsiella pneumoniae HpxO complexed with FAD

Summary for 3RP6

• Entry DOI: 10.2210/pdb3rp6/pdb
• Related: 3RP7 3RP8
• Descriptor: flavoprotein monooxygenase, FLAVIN-ADENINE DINUCLEOTIDE (3 entities in total)
• Functional Keywords: fad-binding protein, monooxygenase, oxidoreductase
• Biological source: Klebsiella pneumoniae
• Total number of polymer chains: 1
• Total formula weight: 46187.05

Authors

Hicks, K.A.,O'Leary, S.E.,Begley, T.P.,Ealick, S.E. (deposition date: 2011-04-26, release date: 2012-05-16, Last modification date: 2024-11-27)

Primary citation

Hicks, K.A.,O'Leary, S.E.,Begley, T.P.,Ealick, S.E.
Structural and Mechanistic Studies of HpxO, a Novel Flavin Adenine Dinucleotide-Dependent Urate Oxidase from Klebsiella pneumoniae.
Biochemistry, 52:477-487, 2013

PubMed Abstract: 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.

PubMed: 23259842
DOI: 10.1021/bi301262p

Experimental method

X-RAY DIFFRACTION (2.2 Å)