Coenzyme Engineering of a Hyperthermophilic 6-Phosphogluconate Dehydrogenase from NADP+ to NAD+ with Its Application to Biobatteries.
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ABSTRACT: Engineering the coenzyme specificity of redox enzymes plays an important role in metabolic engineering, synthetic biology, and biocatalysis, but it has rarely been applied to bioelectrochemistry. Here we develop a rational design strategy to change the coenzyme specificity of 6-phosphogluconate dehydrogenase (6PGDH) from a hyperthermophilic bacterium Thermotoga maritima from its natural coenzyme NADP+ to NAD+. Through amino acid-sequence alignment of NADP+- and NAD+-preferred 6PGDH enzymes and computer-aided substrate-coenzyme docking, the key amino acid residues responsible for binding the phosphate group of NADP+ were identified. Four mutants were obtained via site-directed mutagenesis. The best mutant N32E/R33I/T34I exhibited a ~6.4?×?104-fold reversal of the coenzyme selectivity from NADP+ to NAD+. The maximum power density and current density of the biobattery catalyzed by the mutant were 0.135?mW cm-2 and 0.255?mA cm-2, ~25% higher than those obtained from the wide-type 6PGDH-based biobattery at the room temperature. By using this 6PGDH mutant, the optimal temperature of running the biobattery was as high as 65?°C, leading to a high power density of 1.75?mW cm-2. This study demonstrates coenzyme engineering of a hyperthermophilic 6PGDH and its application to high-temperature biobatteries.
SUBMITTER: Chen H
PROVIDER: S-EPMC5090862 | biostudies-literature | 2016 Nov
REPOSITORIES: biostudies-literature
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