RNA helicase gene CgDBP7 improves the high salt tolerance of Candida glycerinogenes by regulating CgMAK5

Abstract

RNA helicases are a class of highly conserved RNA-binding proteins that unwind double-stranded RNA by hydrolyzing ATP, playing essential roles in processes such as ribosome biogenesis, pre-mRNA splicing, transport, translation, and decay of pre-mRNA. However, their functional roles in the stress responses of Candida glycerinogenes remain uncharacterized to date. Herein, CgDBP7 (C. glycerinogenes DEAD-box RNA helicase DBP7) and its downstream responsive gene CgMAK5 (C. glycerinogenes ATP-dependent RNA helicase MAK5) were first characterized as dual negative regulators of high-salinity tolerance in C. glycerinogenes. Mechanistically, the enhanced high-salinity tolerance of the engineered strain C. glycerinogenes-antiCgDBP7a-antiCgMAK5 was associated with intracellular reactive oxygen species (ROS) detoxification and glycerol biosynthesis. Glycerol acts as an osmoprotectant to balance osmotic pressure under high salt, while efficient ROS detoxification mitigates cellular oxidative damage, collectively boosting tolerance and metabolite production. Under high-salinity conditions, the stress-resistant engineered strain C. glycerinogenes-antiCgDBP7a-antiCgMAK5 achieved a 13.5% and 16.5% increase in glycerol and ethanol titers, respectively. In undetoxified lignocellulosic hydrolysate, this recombinant strain exhibited a further increase of 45.2% in ethanol titer and 13.4% in glycerol titer. Collectively, these findings demonstrate that CgDBP7 and CgMAK5 form a two-layered repressive circuit and serve as key genetic elements for salinity stress adaptation in C. glycerinogenes, providing programmable targets for engineering robust industrial yeast.

Keywords

RNA helicase / High salt tolerance / CgDBP7 / CgMAK5

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Funding

National Natural Science Foundation of China(22278187)

Jiangsu Basic Research Center for Synthetic Biology(Grant No. BK20233003)

RIGHTS & PERMISSIONS

Jiangnan University