Abstract
Very long-chain fatty acids (VLCFAs), fatty acids with chain-length greater than 20 carbons, possess a wide range of biological functions. However, their roles at the molecular level remain largely unknown. In the present study, we screened for multicopy suppressors that rescued temperature-sensitive growth of VLCFA-limited yeast cells, and we identified the VPS21 gene, encoding a Rab GTPase, as such a suppressor. When the vps21Δ mutation was introduced into a deletion mutant of the SUR4 gene, which encodes a VLCFA elongase, a synthetic growth defect was observed. Endosome-mediated vesicular trafficking pathways, including endocytosis and the carboxypeptidase Y (CPY) pathway, were severely impaired in sur4Δ vps21Δ double mutants, while the AP-3 pathway that bypasses the endosome was unaffected. In addition, the sur4Δ mutant also exhibited a synthetic growth defect when combined with the deletion of VPS3, which encodes a subunit of the class C core vacuole/endosome tethering (CORVET) complex that tethers transport vesicles to the late endosome/multivesicular body (MVB). These results suggest that, of all the intracellular trafficking pathways, requirement of VLCFAs is especially high in the endosomal pathways.
Highlights
Very long-chain fatty acids (VLCFAs), fatty acids with chain-length greater than 20 carbons, possess a wide range of biological functions
Complete abrogation of VLCFA synthesis, such as that resulting from a double deletion of the redundant elongases FEN1 and SUR4, is lethal [12], so we first examined the growth of fen1⌬ and sur4⌬ single-mutant cells at high temperature
VLCFAs have essential physiological functions in eukaryotes, and cells carrying double deletions of the redundant yeast Fatty acids (FAs) elongases FEN1 and SUR4, which are involved in VLCFA synthesis, cannot grow in any temperature [12]
Summary
Very long-chain fatty acids (VLCFAs), fatty acids with chain-length greater than 20 carbons, possess a wide range of biological functions. The sur4⌬ mutant exhibited a synthetic growth defect when combined with the deletion of VPS3, which encodes a subunit of the class C core vacuole/ endosome tethering (CORVET) complex that tethers transport vesicles to the late endosome/multivesicular body (MVB). These results suggest that, of all the intracellular trafficking pathways, requirement of VLCFAs is especially high in the endosomal pathways.—Obara, K., R.
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