Algal Protein Kinase, Triacylglycerol Accumulation Regulator1, Modulates Cell Viability and Gametogenesis in Carbon/Nitrogen Imbalanced Conditions

ABSTRACT: Nutrient-deprived microalgae accumulate triacylglycerol (TAG) in lipid droplets. A Dual-specificity tyrosine phosphorylation-regulated kinase, TAG-accumulation-regulator-1 (TAR1) has been shown to be required for acetate-dependent TAG accumulation and degradation of chlorophyll and photosynthesis-related proteins in photomixotrophic nitrogen (N)-deficient conditions (Kajikawa et al. 2015). However, this previous report only examined the particular condition. Here, we report that under photoautotrophic N-deficient conditions, tar1-1 cells, with a mutation in the TAR1 gene, accumulated higher levels of TAG and starch, and maintained higher levels of cell viability and lower levels of H2O2 generation compared to wild-type (WT) cells. Transcriptomic analyses suggest that genes involved in the scavenging of reactive oxygen species, such as APX1, GPX5, PTOX1, TRX7 are not repressed in tar1-1cells. In contrast, mating efficiency and mRNA levels for key regulators in gametogenesis, MID, MTD and FUS, were suppressed in tar1-1 cells. Among the 426 TAR1-dependent phosphoproteins detected by phosphoproteomic analysis, several protein kinases and enzymes related to N assimilation and carbon metabolism are of particular interest. Characterization of these putative downstream factors may elucidate the molecular pathway whereby TAR1 mediates cellular propagation and carbon- and nitrogen- metabolism under C/N imbalance stress conditions.

ORGANISM(S): Chlamydomonas

SUBMITTER: Hideya Fukuzawa 

PROVIDER: PXD012391 | JPOST Repository | Mon Jul 22 00:00:00 BST 2019

REPOSITORIES: jPOST