At least 24 aldehyde reductases from Saccharomyces cerevisiae have been characterized and most function in in situ detoxification of lignocellulosic aldehyde inhibitors, but none is classified into the polyol dehydrogenase (PDH) subfamily of the medium-chain dehydrogenase/reductase (MDR) superfamily. This study confirmed that two (2R,3R)-2,3-butanediol dehydrogenases (BDHs) from industrial (denoted Y)/laboratory (denoted B) strains of S. cerevisiae, Bdh1p(Y)/Bdh1p(B) and Bdh2p(Y)/Bdh2p(B), were members of the PDH subfamily with an NAD(P)H binding domain and a catalytic zinc binding domain, and exhibited reductive activities towards lignocellulosic aldehyde inhibitors, such as acetaldehyde, glycolaldehyde, and furfural. Especially, the highest enzyme activity towards acetaldehyde by Bdh2p(Y) was 117.95 U/mg with cofactor nicotinamide adenine dinucleotide reduced (NADH). Based on the comparative kinetic property analysis, Bdh2p(Y)/Bdh2p(B) possessed higher specific activity, substrate affinity, and catalytic efficiency towards glycolaldehyde than Bdh1p(Y)/Bdh1p(B). This was speculated to be related to their 49% sequence differences and five nonsynonymous substitutions (Ser41Thr, Glu173Gln, Ile270Leu, Ile316Met, and Gly317Cys) occurred in their conserved NAD(P)H binding domains. Compared with BDHs from a laboratory strain, Bdh1p(Y) and Bdh2p(Y) from an industrial strain displayed five nonsynonymous mutations (Thr¹², Asn⁶¹, Glu¹⁶⁸, Val²²², and Ala²³⁵) and three nonsynonymous mutations (Ala³⁴, Ile⁹⁶, and Ala³⁶⁹), respectively. From a first analysis with selected aldehydes, their reductase activities were different from BDHs of laboratory strain, and their catalytic efficiency was higher towards glycolaldehyde and lower towards acetaldehyde. Comparative investigation of kinetic properties of BDHs from S. cerevisiae as aldehyde reductases provides a guideline for their practical applications in in situ detoxification of aldehyde inhibitors during lignocellulose bioconversion.

Key Points

• Two yeast BDHs have enzyme activities for reduction of aldehydes.

• Overexpression of BDHs slightly improves yeast tolerance to acetaldehyde and glycolaldehyde.

• Bdh1p and Bdh2p differ in enzyme kinetic properties.

• BDHs from strains with different genetic backgrounds differ in enzyme kinetic properties.

已经鉴定出至少有24种来自啤酒酵母的醛还原酶，并且在木质纤维素醛抑制剂的原位解毒中发挥最大作用，但没有一个被归类为中链脱氢酶/还原酶（MDR）超家族的多元醇脱氢酶（PDH）子家族。这项研究证实了酿酒酵母的工业（命名为Y）/实验室（命名为B）菌株中的两种（2R，3R）-2,3-丁二醇脱氢酶（BDH）。Bdh1p（Y）/ Bdh1p（B）和Bdh2p（Y）/ Bdh2p（B）是具有NAD（P）H结合结构域和催化性锌结合结构域的PDH亚家族的成员，并且表现出对木质纤维素醛的还原活性抑制剂，例如乙醛，乙醇醛和糠醛。特别是，Bdh2p（Y）对乙醛的最高酶活性为117.95 U / mg，辅因子烟酰胺腺嘌呤二核苷酸还原（NADH）。基于比较动力学性能分析，Bdh2p（Y）/ Bdh2p（B）比Bdh1p（Y）/ Bdh1p（B）具有更高的比活性，底物亲和性和对乙醇醛的催化效率。推测这与它们的49％序列差异有关，并且在其保守的NAD（P）H结合域中出现了五个非同义取代（Ser41Thr，Glu173Gln，Ile270Leu，Ile316Met和Gly317Cys）。¹²，Asn ⁶¹，Glu ¹⁶⁸，Val ²²²和Ala ²³⁵）和三个非同义突变（Ala ³⁴，Ile ⁹⁶和Ala ³⁶⁹）。从对所选醛的首次分析来看，它们的还原酶活性与实验室菌株的BDH不同，并且它们对乙醇醛的催化效率较高，而对乙醛的催化效率较低。酿酒酵母BDH作为醛还原酶的动力学性质的比较研究为其在木质纤维素生物转化过程中醛类抑制剂的原位解毒中的实际应用提供了指南。

关键点

•两种酵母BDH具有还原醛的酶活性。

• BDHs的过度表达可稍微提高酵母对乙醛和乙醇醛的耐受性。

• Bdh1p和Bdh2p的酶动力学特性不同。

•来自具有不同遗传背景的菌株的BDH在酶动力学特性方面有所不同。