Effect of cell cycle arrest on intermediate metabolism in the marine diatom .

The inhibitor NU 2058 [6-(cyclohexylmethoxy)-9-purin-2-amine] leads to G1-phase cell cycle arrest in the marine diatom, by binding to two cyclin-dependent kinases, CDKA1 and CDKA2. NU 2058 has no effect on photosynthetic attributes, such as F/F, chlorophyll /cell, levels of D2 PSII subunits, or RbcL; however, cell cycle arrest leads to unbalanced growth whereby photosynthetic products that can no longer be used for cell division are redirected toward carbohydrates and triacylglycerols (TAGs). Arrested cells up-regulate most genes involved in fatty acid synthesis, including acetyl-CoA carboxylase, and three out of five putative type II diglyceride acyltransferases (DGATs), the enzymes that catalyze TAG production.

Flux balance analysis of primary metabolism in the diatom Phaeodactylum tricornutum.

Diatoms (Bacillarophyceae) are photosynthetic unicellular microalgae that have risen to ecological prominence in oceans over the past 30 million years. They are of interest as potential feedstocks for sustainable biofuels. Maximizing production of these feedstocks will require genetic modifications and an understanding of algal metabolism.

Remodeling of intermediate metabolism in the diatom Phaeodactylum tricornutum under nitrogen stress.

Diatoms are unicellular algae that accumulate significant amounts of triacylglycerols as storage lipids when their growth is limited by nutrients. Using biochemical, physiological, bioinformatics, and reverse genetic approaches, we analyzed how the flux of carbon into lipids is influenced by nitrogen stress in a model diatom, Phaeodactylum tricornutum. Our results reveal that the accumulation of lipids is a consequence of remodeling of intermediate metabolism, especially reactions in the tricarboxylic acid and the urea cycles.