Wang CC, Tsau HW, Chen WT, Huang CY. Identification and characterization of a putative dihydroorotase, KPN01074, from Klebsiella pneumoniae.
Protein J 2010;
29:445-52. [PMID:
20676924 DOI:
10.1007/s10930-010-9272-2]
[Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Dihydroorotase (DHO; EC 3.5.2.3) is an essential metalloenzyme in the biosynthesis of pyrimidine nucleotides. Here, we identified and characterized DHO from the pathogenic bacterium Klebsiella pneumoniae (Kp). The activity of KpDHO toward L: -dihydroorotate was observed with K (m) = 0.04 mM and V (max) = 8.87 mumol/(mg min). Supplementing the standard growth medium with Co2+, Mn2+, Mg2+, or Ni2+ increased enzyme activity. The catalytic activity of KpDHO was inhibited with Co2+, Zn2+, Mn2+, Cd2+, Ni2+, and phosphate ions. Substituting the putative metal binding residues His17, His19, Lys103, His140, His178, and Asp251 with Ala completely abolished KpDHO activity. However, the activity of the mutant D251E was fourfold higher than that of the wild-type protein. On the basis of these biochemical and mutational analyses, KpDHO (KPN01074) was identified as type II DHO.
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