Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Post-Translational Regulation of a Bidomain Glycerol-3-Phosphate Dehydrogenase Catalyzing Glycerol Synthesis under Salinity Stress in Chlamydomonas reinhardtii

Version 1 : Received: 29 February 2024 / Approved: 1 March 2024 / Online: 1 March 2024 (07:48:43 CET)

A peer-reviewed article of this Preprint also exists.

Cruz-Powell, I.; Subedi, B.; Kim, Y.; Morales-Sánchez, D.; Cerutti, H. Post-Translational Regulation of a Bidomain Glycerol-3-Phosphate Dehydrogenase Catalyzing Glycerol Synthesis under Salinity Stress in Chlamydomonas reinhardtii. Phycology 2024, 4, 213-234. Cruz-Powell, I.; Subedi, B.; Kim, Y.; Morales-Sánchez, D.; Cerutti, H. Post-Translational Regulation of a Bidomain Glycerol-3-Phosphate Dehydrogenase Catalyzing Glycerol Synthesis under Salinity Stress in Chlamydomonas reinhardtii. Phycology 2024, 4, 213-234.

Abstract

Core chlorophytes possess glycerol-3-phosphate dehydrogenases (GPDs) with an unusual bidomain structure, consisting of a glycerol-3-phosphate phosphatase (GPP) domain fused to canonical GPD domains. These plastid-localized enzymes have been implicated in stress responses, being required for the synthesis of glycerol under high salinity and triacylglycerols under nutrient deprivation. However, their regulation under varying environmental conditions is poorly understood. C. reinhardtii transgenic strains expressing constitutively bidomain GPD2 did not accumulate glycerol or triacylglycerols in the absence of any environmental stress. Although, the glycerol contents of both wild type and transgenic strains increased significantly upon exposure to high salinity. Cycloheximide, an inhibitor of cytoplasmic protein synthesis, abolished this response in the wild type. In contrast, GPD2 transgenic strains were still capable of glycerol accumulation when cultured in medium containing cycloheximide and NaCl. Thus, pre-existing GPD2 protein appears to become activated for glycerol synthesis upon salt stress. Interestingly, staurosporine, a non-specific inhibitor of protein kinases, prevented this post-translational GPD2 protein activation. Structural modeling analyses suggested that substantial conformational rearrangements, possibly triggered by high salinity, may characterize an active GPD2 GPP domain. Understanding this mechanism(s) may provide insights into the rapid acclimation responses of microalgae to osmotic/salinity stress.

Keywords

osmotic stress; glycerol-3-phospate phosphatase; phosphorylation; kinase inhibition; chloroplast

Subject

Biology and Life Sciences, Life Sciences

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