Expression, purification, and characterization of NADP+-dependent malic enzyme from the oleaginous fungus Mortierella alpina

Appl Biochem Biotechnol. 2014 Aug;173(7):1849-57. doi: 10.1007/s12010-014-0971-6. Epub 2014 May 27.

Abstract

Malic enzymes are a class of oxidative decarboxylases that catalyze the oxidative decarboxylation of malate to pyruvate and carbon dioxide, with concomitant reduction of NAD(P)+ to NAD(P)H. The NADP+-dependent malic enzyme in oleaginous fungi plays a key role in fatty acid biosynthesis. In this study, the malic enzyme-encoding complementary DNA (cDNA) (malE1) from the oleaginous fungus Mortierella alpina was cloned and expressed in Escherichia coli BL21 (DE3). The recombinant protein (MaME) was purified using Ni-NTA affinity chromatography. The purified enzyme used NADP+ as the cofactor. The K m values for L-malate and NADP+ were 2.19±0.01 and 0.38±0.02 mM, respectively, while the V max values were 147±2 and 302±14 U/mg, respectively, at the optimal condition of pH 7.5 and 33 °C. MaME is active in the presence of Mn2+, Mg2+, Co2+, Ni2+, and low concentrations of Zn2+ rather than Ca2+, Cu2+, or high concentrations of Zn2+. Oxaloacetic acid and glyoxylate inhibited the MaME activity by competing with malate, and their K i values were 0.08 and 0.6 mM, respectively.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carboxy-Lyases / genetics*
  • Carboxy-Lyases / isolation & purification
  • Carboxy-Lyases / metabolism*
  • Cloning, Molecular
  • DNA, Complementary / genetics
  • Escherichia coli / genetics
  • Gene Expression
  • Kinetics
  • Malates / metabolism*
  • Metals / pharmacology
  • Mortierella / enzymology*
  • Mortierella / genetics
  • NADP / metabolism*
  • Recombinant Proteins / genetics
  • Recombinant Proteins / isolation & purification
  • Recombinant Proteins / metabolism

Substances

  • DNA, Complementary
  • Malates
  • Metals
  • Recombinant Proteins
  • NADP
  • malic acid
  • Carboxy-Lyases