Coexpression of a carbonyl reductase and glucose 6-phosphate dehydrogenase inPichia pastorisimproves the production of (S)-1-phenyl-1,2-ethanediol

Identification of a novel cytochrome P450 17A1 enzyme and its molecular engineering

Progesterone-17α-hydroxylase (CYP17A) could transform progesterone to 17α-hydroxyprogesterone (17-HP).

Ketoreductase catalyzed stereoselective bioreduction of α-nitro ketones

We report here the stereoselective bioreduction of α-nitro ketones catalyzed by ketoreductases (KREDs) with publicly known sequences. YGL039w and RasADH/SyADH were able to reduce 23 class I substrates (1-aryl-2-nitro-1-ethanone (1)) and ten class II substrates (1-aryloxy-3-nitro-2-propanone (4)) to furnish both enantiomers of the corresponding β-nitro alcohols, with good-to-excellent conversions (up to >99%) and enantioselectivities (up to >99% ee) being achieved in most cases. To the best of our knowledge, KRED-mediated reduction of class II α-nitro ketones (1-aryloxy-3-nitro-2-propanone (4)) is unprecedented. Select β-nitro alcohols, including the synthetic intermediates of bioactive molecules (R)-tembamide, (S)-tembamide, (S)-moprolol, (S)-toliprolol and (S)-propanolol, were stereoselectively synthesized in preparative scale with 42% to 90% isolated yields, showcasing the practical potential of our developed system in organic synthesis. Finally, the advantage of using KREDs with known sequence was demonstrated by whole-cell catalysis, in which β-nitro alcohol (R)-2k, the key synthetic intermediate of hypoglycemic natural product (R)-tembamide, was produced in a space-time yield of 178 g L-1 d-1 as well as 95% ee by employing the whole cells of a recombinant E. coli strain coexpressing RasADH and glucose dehydrogenase as the biocatalyst.

Comparative performance of S-adenosyl-L-methionine biosynthesis and degradation in Pichia pastoris using different promoters and novel consumption inhibitors

The yeast Pichia pastoris is a widely used host for recombinant protein expression, and has recently been engineered for whole-cell biocatalysis. The inducible P(AOX) and constitutive P(GAP) promoters are commonly employed. In this study, the S-adenosyl-L-methionine (SAM) biosynthesis and degradation efficiency of two P. pastoris strains were compared, and novel inhibitors that suppress SAM degradation were characterized. The strains exhibited clear physiological differences. P(GAP)-Pichia showed higher transcription and activity of SAM synthetase, and the rapid cell growth led to higher levels of spermidine synthesis from SAM. In contrast, P(AOX)-Pichia synthesized higher levels of glutathione from SAM, and this strain responded to hydrogen peroxide formation during methanol utilization. Aristeromycin proved an efficient inhibitor of SAM degradation in P(AOX)-Pichia; 0.02 mg/L led to a 36.36% reduction in the ratio of glutathionine:SAM, and SAM accumulation was enhanced by 7.74% to 11.83 g/L. Ethanol was an even more efficient inhibitor of SAM consumption in P(GAP)-Pichia; 8 g/L resulted in a 73.68% decrease in the ratio of SPD:SAM, and SAM production was elevated by 54.55% to 0.17 g/L/h.