Characterization of the Nuclear Proteome of Chlamydomonas in Response to Salt Stress

Abstract

Microalgae biomass is considered a promising alternative feedstock for biodiesel production due to its high productivity of neutral lipids, especially under abiotic stress conditions. Among the unicellular microalgae that show this characteristic, Chlamydomonas reinhardtii appears as one of the most important model species with increased lipid production under abiotic stress conditions. In this study, we show that C. reinhardtii cells cultivated under mixotrophic condition supplemented with 0.1 M of NaCl rapidly raise their intracellular amount of neutral lipids without a reduction in their cellular growth rate, representing a promising condition for biomass production toward bioenergy applications. The nuclear proteome of these cells was investigated, and we identified 323 proteins with an enrichment of almost 60% of nuclear proteins in the total dataset. We found 61 proteins differentially regulated upon salt treatment, including proteins annotated in functional categories related to translation and nucleosome assembly functions. Additionally, we identified transcription factor proteins (TFs) and analyzed their likely transcription factor-binding regulatory elements, identifying target genes related to lipid metabolism and kinase functions, indicating possible regulatory pathways of lipid biosynthesis. Together, these data can help understand regulatory nuclear mechanisms, leading to an increase in lipids in the first 24 h of salt stress.