Increase in cellular triacylglycerol content and emergence of large ER-associated lipid droplets in the absence of CDP-DG synthase function.
Bottom Line: Using two species of fission yeast, we show that cycling cells deficient in the function of the ER-resident CDP-DG synthase Cds1 exhibit markedly increased triacylglycerol content and assemble large lipid droplets closely associated with the ER membranes.We demonstrate that these unusual structures recruit the triacylglycerol synthesis machinery and grow by expansion rather than by fusion.Our results suggest that interfering with the CDP-DG route of phosphatidic acid utilization rewires cellular metabolism to adopt a triacylglycerol-rich lifestyle reliant on the Kennedy pathway.
Affiliation: Temasek Life Sciences Laboratory, 117604 Singapore Department of Biological Sciences, National University of Singapore, 117543 Singapore.Show MeSH
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Mentions: One of the mutants, #185, exhibited unusually large spherical ER structures after incubation at the restrictive temperature of 36°C, prompting us to name it bubble1 (bbl1; Figure 1A). By backcrossing the #185 bbl1 strain to the wild-type strain and scoring segregation of phenotypes of progeny, we verified that the bbl phenotype was due to a mutation at a single genomic locus. On shift to the restrictive temperature, bbl1 colonies exhibited an increase in phloxine B staining suggestive of some cell death, but most cells growing in liquid cultures were able to divide normally in the rich, yeast extract–based medium at both 24°C (2.1 vs. 2 h for wild-type and bbl1 cells, respectively) and 36°C (2.2 vs. 2.1 h for wild-type and bbl1 cells, respectively).
Affiliation: Temasek Life Sciences Laboratory, 117604 Singapore Department of Biological Sciences, National University of Singapore, 117543 Singapore.