Aldehydes are the main inhibitors generated during the pretreatment of lignocellulosic biomass, which can inhibit cell growth and disturb subsequent fermentation. Saccharomyces cerevisiae has the intrinsic ability to in situ detoxify aldehydes to their less toxic or nontoxic alcohols by numerous aldehyde dehydrogenases/reductases during the lag phase. Herein, we report that an uncharacterized open reading frame YMR152W from S. cerevisiae encodes a novel aldehyde reductase with catalytic functions for reduction of at least six aldehydes, including two furan aldehydes (furfural and 5-hydroxymethylfurfural), three aliphatic aldehydes (acetaldehyde, glycolaldehyde, and 3-methylbutanal), and an aromatic aldehyde (benzaldehyde) with NADH or NADPH as the co-factor. Particularly, Ymr152wp displayed the highest specific activity (190.86 U/mg), and the best catalytic rate constant (K_cat), catalytic efficiency (K_cat/K_m), and affinity (K_m) when acetaldehyde was used as the substrate with NADH as the co-factor. The optimum pH of Ymr152wp is acidic (pH 5.0–6.0), but this enzyme is more stable in alkaline conditions (pH 8.0). Metal ions, chemical protective additives, salts, and substrates could stimulate or inhibit enzyme activities of Ymr152wp in varying degrees. Ymr152wp was classified into the quinone oxidoreductase (QOR) subfamily of the medium-chain dehydrogenase/reductase (MDR) family based on the results of amino acid sequence analysis and phylogenetic analysis. Although Ymr152wp was grouped into the QOR family, no quinone reductase activity was observed using typical quinones (9,10-phenanthrenequinone, 1,2-naphthoquinone, and p-benzoquinone) as the substrates. This study provides guidelines for exploring more uncharacterized aldehyde reductases in S. cerevisiae for in situ detoxification of aldehyde inhibitors derived from lignocellulosic hydrolysis.

醛是木质纤维素生物质预处理过程中产生的主要抑制剂，可抑制细胞生长并干扰随后的发酵。酿酒酵母具有在滞后阶段通过多种醛脱氢酶/还原酶将醛原位解毒成毒性较小或无毒的醇类的固有能力。在此，我们报道了来自酿酒酵母的未表征的开放阅读框YMR152W编码具有催化功能的新型醛还原酶，可还原至少六个醛，包括两个呋喃醛（糠醛和5-羟甲基糠醛），三个脂族醛（乙醛，乙醇醛和3-甲基丁醛）和一个芳香醛（苯甲醛） NADH或NADPH作为辅助因子。特别地，Ymr152wp表现出最高的比活度（190.86 U / mg），最佳的催化速率常数（K _cat），最佳的催化效率（K _cat / K _m）和亲和力（K _m）时，以乙醛为底物，以NADH为辅因子。Ymr152wp的最佳pH值为酸性（pH 5.0-6.0），但该酶在碱性条件（pH 8.0）下更稳定。金属离子，化学保护性添加剂，盐和底物可以不同程度地刺激或抑制Ymr152wp的酶活性。根据氨基酸序列分析和系统发育分析的结果，将Ymr152wp归类为中链脱氢酶/还原酶（MDR）家族的醌氧化还原酶（QOR）亚家族。尽管Ymr152wp属于QOR家族，但是使用典型的醌类（9,10-菲醌，1,2-萘醌和p-苯醌）作为底物。本研究为探索更多未表征的醛还原酶准则酿酒酵母为原位从木质纤维素水解衍生的醛抑制剂解毒。