Einhardtii in which C18:36,9,12 and C18:46,9,12,15 are replaced by C18:35,9,12 and C18:45,9,12,15, respectively [141]. The relative abundance of fatty acids in C. zofingiensis varies tremendously based on culture conditions, for instance, the main monounsaturated fatty acid C18:19 has a considerably larger percentage below ND + HL than beneath favorable growth situations, using a reduced percentage of polyunsaturated fatty acids [13]. As well as the polar glycerolipids present in C. reinhardtii, e.g., monogalactosyl diacylglycerol (MGDG), digalactosyl diacylglycerol (DGDG), sulfoquinovosyl diacylglycerol (SQDG), phosphatidylglycerol (PG), phosphatidylinositol (PI), phosphatidylethanolamine (PE) and diacylglycerol-N,N,N-trimethylhomoserine (DGTS), C. zofingiensis includes phosphatidylcholine (Pc) as well [18, 37, 38]. As indicated in Fig. 4 according to the data from Liu et al. [37], below nitrogen-replete favorable development situations, the lipid fraction accounts for only a little proportion of cell mass, of which membrane lipids particularly the glycolipids MGDG and DGDG would be the important lipid classes. By contrast, below such stress condition as ND, the lipid fraction dominates the proportion of cell mass, contributed by the huge increase of TAG. Polar lipids, however, lower severely in their proportion.Fig. four Profiles of fatty acids and glycerolipids in C. zofingiensis under nitrogen replete (NR) and nitrogen deprivation (ND) conditions. DGDG, digalactosyl diacylglycerol; DGTS, diacylglycerol-N,N,N-tri methylhomoserine; MGDG, monogalactosyl diacylglycerol; SQDG, sulfoquinovosyl diacylglycerol; PE, phosphatidylethanolamine; PG, phosphatidylglycerol; PI, phosphatidylinositol; TAG, triacylglycerol; TFA, total fatty acidsFatty acid biosynthesis, desaturation and degradationGreen algae, similar to vascular plants, perform de novo fatty acid synthesis in the chloroplast, working with acetyl-CoA because the precursor and constructing block [141]. Several routes are proposed for making acetyl-CoA: from pyruvate mediated by pyruvate dehydrogenase complicated (PDHC), from pyruvate by means of PDHC bypass, from citrate through the ATP-citrate lyase (ACL) reaction, and from acetylcarnitine via carnitine acetyltransferase reaction [144]. C. zofingiensis genome harbors genes encoding enzymes involved inside the initial 3 routes [37]. Taking into account the predicted subcellular localization data and transcriptomics data [18, 37, 38], C. zofingiensis likely employs each PDHC and PDHC bypass routes, but mainly the former one, to provide acetyl-CoA in the chloroplast for fatty acid synthesis. De novo fatty acid synthesis within the chloroplast consists of a series of enzymatic steps mediated by acetyl-CoAZhang et al. Biotechnol Biofuels(2021) 14:Page ten ofcarboxylase (ACCase), malonyl-CoA:acyl carrier protein (ACP) transacylase (MCT), and sort II fatty acid synthase (FAS), an easily dissociable multisubunit complicated (Fig. five). The formation of malonyl-CoA from acetyl-CoA, a committed step in fatty acid synthesis, is catalyzed by ACCase [145]. The chloroplast-localized ACCase in C. zofingiensis is a tetrasubunit enzyme CXCR4 manufacturer consisting of -carboxyltransferase, -carboxyltransferase, biotin carboxyl carrier protein, and biotin carboxylase.These subunits are effectively correlated at the transcriptional level [18, 33, 37, 39]. Malonyl-CoA must be c-Raf list converted to malonyl-acyl carrier protein (ACP), by way of the action of MCT, prior to entering the subsequent condensation reactions for acyl chai.
