Expression and Characterization of a Novel Propionyl-CoA Dehydrogenase Gene from Candida rugosa in Pichia pastoris

Abstract

The propionyl-CoA dehydrogenase (PACD) gene was firstly cloned from Candida rugosa by the cDNA RACE technique. The 6× His-tagged recombinant PACD gene was expressed in Pichia pastoris GS115 and purified with Ni-NTA affinity chromatography. SDS-PAGE analysis and Western blotting revealed that the molecular mass of the purified PACD was 49 kDa. The results showed that the recombinant protein had the activity of catalyzing propionyl-CoA to acrylyl-CoA. The K (m), k (cat), and V (max) values of the purified PACD were calculated to be 40.86 μM, 0.566 s(-1) and 0.693 U mg(-1) min(-1). The optimal temperature and pH of the purified PACD were 30 °C and 7.0, respectively. The recombinant PACD maintained 76.3%, 30.1%, and 4.3% of its original activity after 2 h incubation in standard buffer at 30, 40, and 50 °C, respectively. Mg(2+) had an activating effect on the enzyme, while Mn(2+), Ca(2+), Zn(2+), and Cu(2+) had weak inhibition. Since PACD catalyzed the key step (from propionyl-CoA to acrylyl-CoA) in the modified β-oxidation pathway from glucose to 3-hydroxypropionic acid (3-HP), the integration of recombinant PACD could benefit the engineered strains for effective production of 3-HP from the most abundant biomass-sugars.