Heterologous expression and enzymatic identification of two novel soluble pyridine nucleotide transhydrogenases from Acidobacteria bacterium KBS 146 and Nocardia jiangxiensis

Abstract

Soluble pyridine nucleotide transhydrogenase (STH), catalyzes a reversible hydrogen transfer between NADH and NADPH, is widely utilized in cofactor engineering. In the present study, we expanded the distribution range of STH to more unreported bacteria. Meanwhile, STH was mainly found in α, γ, δ-proteobacteria, acidobacteria, actinobacteria and planctomycetes. The enzymological properties of two novel STHs from Acidobacteria bacterium KBS 146 (AbSTH) and Nocardia jiangxiensis (NjSTH) were characterized. The optimum temperature and pH of AbSTH and NjSTH were pH 6.2 and 35 °C, pH 5.7 and 50 °C, respectively. When using thio-NAD+ as a hydrogen accepter, the 1/K m and k cat/K m for NADH of AbSTH were 1.8 and 1.7-fold greater than NADPH, whereas the 1/K m and k cat/K m of NjSTH for NADPH were 2.0 and 2.2-fold greater than NADH. The physiological hydrogen donor substrate of AbSTH and NjSTH may be NADH and NADPH, respectively. AbSTH activity was inhibited by ATP and strongly stimulated by ADP and AMP. These results may provide new insights into the physiological roles and cofactor engineering application of STH. Supplemental data for this article is available online at https://doi.org/10.1080/13102818.2021.1988708 .