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, specially under abiotic stress conditions. Among the unicellular microalgae that show this characteristic, Chlamydomonas reinhardtii appears as one of the most important model species that have increased lipids production under abiotic stress conditions. In this study, we show that cells cultivated under mixotrophic condition supplemented with 0.1 M of NaCl rapidly raises their amount of neutral lipids in C. reinhardtii without reduction of their cellular growth rate, being therefore a promising condition for biomass towards bioenergy production. The nuclear proteome of these cells was investigated where 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, among others. Additionally, we identified Transcription factor proteins (TFs) and analyzed their likely Transcription factors-binding regulatory elements identifying target genes related to lipids metabolism and kinase functions, indicating possible regulatory pathways of lipids biosynthesis. Together these data can help understand regulatory nuclear mechanisms leading to an increase of lipids in the first 24h of salt stress 0.1M NaCl.