Date of this Version
Cruz-Powell, Itzela (2021) Characterization of a novel glycerol-3-phosphate dehydrogenase (GPD2) in the alga Chlamydomonas reinhardtii. Dissertations and Theses in Biological Sciences.
The green alga Chlamydomonas reinhardtii, like many eukaryotic microalgae, accumulates triacylglycerol (TAG) under certain environmental stresses, such as nitrogen deprivation. TAG is of interest because it is an essential precursor for biofuel production. Canonical glycerol-3-phosphate dehydrogenases catalyze the synthesis of glycerol-3-phosphate (G3P), a key precursor for glycerolipid and TAG synthesis in eukaryotes. The C. reinhardtii genome encodes six GPD homologs. Interestingly, GPD2 is a novel multidomain enzyme, consisting of a phosphatase motif fused to a G3P dehydrogenase domain. GPD2 expression is significantly up-regulated under nutrient deprivation or high salinity, coincidental with the accumulation of TAG or glycerol. Conversely, RNA-mediated silencing of GPD2 reduces TAG and glycerol production under the same stresses. Based on these observations, we hypothesize that GPD2 contributes to the synthesis of both glycerol and TAG, depending on the environmental conditions. Thus, our goals are to decipher how the enzymatic activities (i.e., dehydrogenase and phosphatase) of GPD2 are regulated under different environmental conditions. Understanding how cells regulate GPD2 enzymatic activities, and what other components GPD2 may interact with, may contribute to broadening our biochemical and cytological understanding of algal TAG and glycerol metabolic pathways, with possible implications for biotechnological biofuel/biomaterial production.
Advisor: Heriberto Cerutti