Project description:Pseudozyma hubeiensis is a basidiomycete yeast that has the highly desirable traits for lignocellulose valorisation of being equally efficient at utilization of glucose and xylose, and capable of their co-utilization. The species has previously mainly been studied for its capacity to produce secreted biosurfactants in the form of mannosylerythritol lipids, but it is also an oleaginous species capable of accumulating high levels of triacylglycerol storage lipids during nutrient starvation. In this study, we aimed to further characterize the oleaginous nature of P. hubeiensis by evaluating metabolism and gene expression responses during storage lipid formation conditions with glucose or xylose as a carbon source.
Project description:Oleaginous yeasts are capable of accumulating high levels of intracellular storage lipids from excess carbon during times when other key nutrients are limited. The basidiomycete yeast Rhodosporidium toruloides is an emerging host for microbial cell factory applications thanks to its naturally high lipid and carotenoid production. However, the engineering toolbox in this non-model host is limited and is currently a bottleneck for implementation of metabolic engineering strategies. In this study, we performed differential gene expression analysis with the goal to identify promoters that are strongly induced or repressed by nitrogen-limitation, a condition that is commonly used to induce lipid accumulation in oleaginous yeasts. The genome-wide transcriptional response of R. toruloides BOT-A2 was analysed using RNAseq during exponential growth and nitrogen-starvation, with either glucose or xylose as the sole carbon source. To validate the differential gene expression findings, reporter genes were constructed by placing the candidate promoters in control of a fluorescent protein, integrated in BOT-A2 and evaluated in vivo.
Project description:Lipid accumulation by oleaginous microorganisms is of great scientific interest and biotechnological potential. While nitrogen limitation has been routinely employed, low-cost raw materials usually contain rich nitrogenous components, thus preventing from efficient lipid production. Inorganic phosphate (Pi) limitation has been found sufficient to promote conversion of sugars into lipids, yet the molecular basis of cellular response to Pi-limitation and concurrent lipid accumulation remains elusive. Here we performed multi-omic analyses of the oleaginous yeast Rhodosporidium toruloides to shield lights on Pi-limitation induced lipid accumulation. Samples were prepared under Pi-limited as well as Pi-replete chemostat conditions, and subjected to analysis at the transcriptomic, proteomic and metabolomic level. In total, 7970 genes, 4212 proteins and 123 metabolites were identified. Results showed that Pi-limitation facilitates up-regulation of Pi-associated metabolism, RNA degradation and triacylglycerol biosynthesis, while down-regulation of ribosome biosynthesis and tricarboxylic acid cycle. Pi-limitation leads to de-phosphorylation of adenosine monophosphate, the allosteric activator of isocitrate dehydrogenase key to lipid biosynthesis. It was found that NADPH, the key cofactor for fatty acid biosynthesis, is limited due to reduced flux through the pentose phosphate pathway and transhydrogenation cycle, and that this can be overcomed by overexpression of an endogenous malic enzyme. These phenomena are found distinctive from those under nitrogen-limitation. The information greatly enriches our understanding on microbial oleaginicity and Pi-related metabolism. Importantly, systems data may facilitate designing advanced cell factories for production of lipids and related oleochemicals.
Project description:First part of the time-course transcriptomic profilling of the oleaginous yeast Yarrowia lipolytica, obtained during a controlled decellerostat (D-stat) setup. A nitrogen limitation was applied during the course of the D-stat to initiate and control de novo biolipid synthesis. Yarrowia lipolytica Agilent microarray, one-color staining. Each time sample was spotted in triplicate. A reference condition was spotted in quadruplicate, based on a RNA pool from three samples obtained during the biomass production phase.
Project description:Lysine acetylation of proteins, a major post-translational modification, plays a critical regulatory role in almost every aspects in both eukaryotes and prokaryotes. Yarrowia lipolytica, an oleaginous yeast, is considered as a model for bio-oil production due to its ability to accumulate a large amount of lipids. However, the function of lysine acetylation in this organism is elusive. Here, we performed a global acetylproteome analysis of Y. lipolytica ACA-DC 50109. In total, 3163 lysine acetylation sites were identified in 1428 proteins, which account for 22.1% of the total proteins in the cell. Fifteen conserved acetylation motifs were detected. The acetylated proteins participate in a wide variety of biological processes. Notably, a total of 65 enzymes involved in lipid biosynthesis were found to be acetylated. The acetylation sites are distributed in almost every type of conserved domains in the multi-enzymatic complexes of fatty acid synthetases, suggesting an important regulatory role of lysine acetylation in lipid metabolism. Moreover, protein interaction network analysis reveals that diverse interactions are modulated by protein acetylation. The provided dataset probably illuminates the crucial role of reversible acetylation in oleaginous microorganisms, and serves as an important resource for exploring the physiological role of lysine acetylation in eukaryotes.
Project description:Our study is the first investigation of proteome of oleaginous yeast Rhotodorula toruloides during conversion of xylose into lipids. We performed comparative proteomics of R. toruloides during cultivation of two carbon sources: glucose and xylose. Proteome analysis revealed significantly lower levels of ribosomal proteins and translation associated factors in xylose-grown cells as compared to glucose-grown cells. We showed that proteins involved in sugar transport, phospholipid and leucine biosynthesis as well as peroxisomal beta-oxidation and oxidative stress response were differentially regulated in response to carbon source.