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Published on: July 5, 2024
Engineering d-Lactate Dehydrogenase to Favor an Non-natural Cofactor Nicotinamide Cytosine Dinucleotide
Yuxue Liu1, Qing Li1, Lei Wang1
1Laboratory of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian, 116023, P. R. China.
Abstract:
Synthetic nicotinamide adenine dinucleotide (NAD) analogues are of great scientific and biotechnological interest. One such analogue, nicotinamide cytosine dinucleotide (NCD), has been successfully applied to creating bioorthogonal redox systems. Yet, only a few redox enzymes have been devised to favor NCD. We have engineered Lactobacillus helveticus-derived NAD-dependent d-lactate dehydrogenase (LhDLDH) to favor NCD by semirational design. Sequence alignment and structural analysis revealed that amino acid residues I177 and N213 form a "gate" guarding the NAD adenine moiety binding cavity. Saturated mutagenesis libraries were constructed by using the mutant LhDLDH-V152R as the parental sequence. Mutants were obtained with good catalytic efficiency, and NCD preference increased by up to 940-fold. Experiments showed that Escherichia coli cells expressing mutants with higher NCD preference afforded much less d-lactate, thus suggesting the potential to construct NCD-mediated orthogonal metabolism.
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