Biochemical and structural characterization of Klebsiella pneumoniae oxamate amidohydrolase in the uric acid degradation pathway.
HpxW from the ubiquitous pathogen Klebsiella pneumoniae is involved in a novel uric acid degradation pathway downstream from the formation of oxalurate. Specifically, HpxW is an oxamate amidohydrolase which catalyzes the conversion of oxamate to oxalate and is a member of the Ntn-hydrolase superfamily. HpxW is autoprocessed from an inactive precursor to form a heterodimer, resulting in a 35.5 kDa α subunit and a 20 kDa β subunit. Here, the structure of HpxW is presented and the substrate complex is modeled. In addition, the steady-state kinetics of this enzyme and two active-site variants were characterized. These structural and biochemical studies provide further insight into this class of enzymes and allow a mechanism for catalysis consistent with other members of the Ntn-hydrolase superfamily to be proposed.
Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.
Katherine A
KA
Hicks
Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.
Steven E
SE
Ealick
D000581:Amidohydrolases / Q000737:chemistry* / Q000378:metabolism*; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D006801:Humans; D007710:Klebsiella Infections / Q000382:microbiology; D007711:Klebsiella pneumoniae / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism; D008958:Models, Molecular; D011487:Protein Conformation; D013379:Substrate Specificity; D014527:Uric Acid / Q000378:metabolism*
D014527:Uric Acid; D000581:Amidohydrolases; C438834:N-terminal nucleophile hydrolase
Ntn-hydrolase superfamily; glutamyltranspeptidase; selenium SAD phasing; uric acid degradation