RESUMO
Cell size and morphology are key adaptive features that influence almost all aspects of cellular physiology such as cell cycle and lipid metabolism. Here we report the role of a transcription factor Suppressor Phenotype of Ty elements insertion 10 (SPT10) of Saccharomyces cerevisiae in regulating cell cycle, cell size and lipid metabolism in concert, in addition to its defined role of histone gene expression. Morphological and biochemical analyses of spt10Δ strain show an abnormal cell size, cell cycle and lipid levels. The expression of Spt10p in spt10Δ strain helps the cell revert to typical wild-type phenotypes. SPT10 controls lipid metabolism by negatively regulating the expression of lipid biosynthetic genes, and positively regulating the expression of the lipid hydrolyzing genes. Spt10p helps in maintaining the cell size by regulating the amount of carbon flux into the phospholipid constituents of the cell membranes. On the contrary, storage lipids have no role in regulating the cell size. An exogenous supply of phosphatidic acid increases the cell size, proving the positive impact of the phospholipids on cell size modulation. SPT10 affects cell cycle, cell size and lipid metabolism by an orchestrated transcriptional regulation of the corresponding genes.
Assuntos
Histona Acetiltransferases/metabolismo , Metabolismo dos Lipídeos , Fosfolipídeos/fisiologia , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/citologia , Saccharomyces cerevisiae/metabolismo , Fatores de Transcrição/metabolismo , Carbono/metabolismo , Ciclo Celular , DNA Fúngico/metabolismo , Ensaio de Desvio de Mobilidade Eletroforética , Regulação Fúngica da Expressão Gênica , Genes Fúngicos , Teste de Complementação Genética , Metabolismo dos Lipídeos/genética , Lipídeos/biossíntese , Ácidos Fosfatídicos/farmacologia , Ligação Proteica , Saccharomyces cerevisiae/genética , Transcrição Gênica , Regulação para CimaRESUMO
A recent study showed that deletion of the gene encoding the transcription regulator SuPpressor of Ty10 (SPT10) increases total phospholipids, and our previous study established a critical link between phospholipids and the mevalonate/ergosterol (MEV/ERG) pathway, which synthesises triterpenes. This study aims to use spt10Δ yeast to improve triterpene production. Though MEV/ERG pathway was highly expressed in spt10Δ yeast, results showed insufficient accumulation of key metabolites and also revealed massive endoplasmic reticulum (ER) degradation. We found a stable, massive ER structure when we overexpressed diacylglycerol kinase1 (DGK1OE ) in spt10Δ yeast. Analyses of ER-stress and autophagy suggest that DGK1OE in the spt10Δ strain decreased autophagy, resulting in increased MEV/ERG pathway activity. Heterologous expression of ß-amyrin synthase showed significant production of the triterpene ß-amyrin in DGK1OE spt10Δ yeast. Overall, our study provides a strategic approach to improve triterpene production by increasing ER biogenesis while limiting ER degradation.
Assuntos
Autofagia , Diacilglicerol Quinase , Proteínas de Saccharomyces cerevisiae , Triterpenos , Autofagia/genética , Autofagia/fisiologia , Diacilglicerol Quinase/genética , Diacilglicerol Quinase/metabolismo , Retículo Endoplasmático/genética , Retículo Endoplasmático/metabolismo , Estresse do Retículo Endoplasmático , Histona Acetiltransferases/metabolismo , Fosfolipídeos/metabolismo , Proteínas Repressoras/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Fatores de Transcrição/metabolismo , Triterpenos/metabolismoRESUMO
Seipin is a key protein in the assembly of cytoplasmic lipid droplets (cLDs) and their maintenance at endoplasmic reticulum (ER)-LD junctions; the absence of seipin results in generalized lipodystrophy. How seipin mediates LD dynamics and prevents lipodystrophy are not well understood. New evidence suggests that seipin attracts triglyceride monomers from the ER to sites of droplet formation. By contrast, seipin may not be directly involved in the assembly of nuclear LDs and may actually suppress their formation at a distance. Seipin promotes adipogenesis, but lipodystrophy may also involve postadipogenic effects. We hypothesize that among these are a cycle of runaway lipolysis and lipotoxicity caused by aberrant LDs, resulting in a depletion of fat stores and a failure of adipose and other cells to thrive.