Quantitative proteomic analyses reveal the impact of nitrogen starvation on the proteome of the model diatom Phaeodactylum tricornutum

Abstract

Diatoms are one of the largest groups in phytoplankton biodiversity. Understanding their response to nitrogen variations, present from micromolar to near-zero levels in oceans and fresh waters, is essential to comprehend their ecological success. Nitrogen starvation is used in biotechnological processes, to trigger the remodelling of carbon metabolism in the direction of fatty acids and triacylglycerol synthesis. We evaluated whole proteome changes in Phaeodactylum tricornutum after seven days of cultivation with 5.5 mM nitrate (+N) or without any nitrogen source (-N). On a total of 3,768 proteins detected in biological replicates, our analysis pointed to 384 differentially abundant proteins. Analysis of proteins of lower abundance in -N revealed an arrest of amino acid and protein syntheses, a remodeling of nitrogen metabolism and a decrease of the proteasome abundance suggesting a decline in unselective whole-proteome decay. Analysis of proteins of higher abundance revealed the setting up of a general nitrogen scavenging system dependent on deaminases. The increase of a plastid palmitoyl-ACP desaturase appeared as a hallmark of carbon metabolism rewiring in the direction of fatty acid and triacylglycerol synthesis. This dataset is also valuable to select gene candidates for improved biotechnological properties.

Differential protein analysis of saline-alkali promoting the oil accumulation in Nitzschia palea

“…With the increasing salinisation of water bodies and scarcity of freshwater resources, algae such as Microcystis aeruginosa , Scenedesmus obliquus , Isochrysis galbana Parke and Tribonema minus are considered as the best raw materials for the development of sustainable energy production [ 68 , 69 ]. Studies have shown that Microcystis aeruginosa has a simple composition of lipids and fatty acids that can be easily transesterified to biodiesel [ 70 ].…”

“…Phaeodactylum tricornutum as a model organism for diatom, the proteomics of is mainly focused on carbon and nitrogen metabolism, fatty acid and lipid synthesis of diatoms under N and P limiting conditions. The intracellular changes in Phaeodactylum tricornutum under different conditions were revealed at the protein level, such as the increase of plastidial palmitoyl- ACP desaturase, which is an important marker of carbon metabolism towards fatty acid and triacylglycerol synthesis [ 17 – 20 ]. Dunaliella salina is often used as a model algal species for halophilic algae and the molecular mechanisms of its salt tolerance indicated that salinity-regulated proteins were mainly involved in the Calvin cycle, energy production, protein synthesis/degradation, membrane structure stabilisation and signal transduction pathways [ 21 , 22 ].…”