One 3-oxoacyl-(acyl-Carrier-protein) reductase functions as 17β-hydroxysteroid dehydrogenase in the estrogen-degrading Pseudomonas putida SJTE-1

Abstract

Pseudomonas putida SJTE-1 can utilize 17β-estradiol (E2) as its carbon source, while the enzymes for E2 transformation in this strain is still unclear. 17β-hydroxysteroid dehydrogenases (17β-HSD) can catalyze the reduction/oxidation at C17 site of steroid hormone specifically, critical for steroid transformation. Here a novel 3-oxoacyl-(acyl-carrier protein) (ACP) reductase (ANI02794.1) was identified as it could bβ-estradiol, and was proved to be capable of functioning as 17β-HSD. Sequences alignment showed it contained the two consensus regions and the conserved residues of short-chain dehydrogenase/reductase (SDR). Its encoding gene was cloned and over-expressed in Escherichia coli BL21(DE3) strain, and the recombinant protein was purified by the metal-ion affinity chromatography with the yield of 18 mg/L culture. HPLC (High Performance Liquid Chromatography) detection showed this enzyme could convert 17β-estradiol into estrone using NAD+ as cofactor. Its Km value was 0.082 mM and its Vmax value was 0.81 mM/s; its transformation efficiency of 17β-estradiol into estrone was over 96.6% in five minutes. Its optimal temperature was 37 °C and optimal was pH 9.0; the divalent ions had different effects on the enzymatic activity. In conclusion, this 3-oxoacyl-ACP reductase functioned as 17β-HSD in P. putida SJTE-1 and played important role in its estrogen metabolism.