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Localization of Opi1p FFAT to lipid droplets during inositol starvation in Saccharomyces cerevisiae
Author(s) -
Chang YuFang,
Gaspar Maria,
Henry Susan A.
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.585.12
Subject(s) - inositol , lipid droplet , endoplasmic reticulum , mutant , saccharomyces cerevisiae , phosphatidic acid , biochemistry , microbiology and biotechnology , biogenesis , chemistry , biology , yeast , phospholipid , gene , receptor , membrane
Phosphatidic acid (PA) is a signaling lipid that plays an important role in mediating phospholipid biosynthesis. However, the subcellular distribution of PA remains elusive. In this study, PA levels were manipulated by shifting cells from inositol‐containing medium to inositol‐lacking medium. A mutated form of the Opi1p repressor, Opi1p FFAT , which loses the interaction with the endoplasmic reticulum (ER) protein Scs2p but contains a PA‐binding domain, relocalizes to lipid droplets (LDs) after 2‐h of inositol starvation. Opi1p FFAT localization was also monitored in mutant cells with defects in triacylglycerol (TAG) metabolism, including pah1 Δ and lro1 Δ dga1 Δ for TAG biosynthesis, and tgl3 Δ tgl4 Δ tgl5 Δ for TAG mobilization. Opi1p FFAT localized to LDs in the tgl3 Δ tgl4 Δ tgl5 Δ mutant, but did not localize to LDs in cells unable to synthesize TAG. Another mutated form of Opi1p, Opi1p FFAT /PAc4m , which carries mutations in both FFAT and PA‐binding domains, was also examined. Opi1p FFAT/ PAc4m did not localize to LDs, but remained in the nucleus. These results suggest Opi1p FFAT binds to a specific pool of PA that is actively involved in TAG synthesis. Fld1p, a human seipin homolog in yeast that binds to the junction of LDs and ER, was shown to colocalize with Opi1p FFAT followed by 2‐h inositol starvation, suggesting a pool of PA to the sites of LD biogenesis. Supported by NIH grant GM019629.