title: Long-chain bases of sphingolipids are transported into cells via the acyl-CoA synthetases.
abstract: Transport of dietary lipids into small-intestinal epithelial cells is pathologically and nutritionally important. However, lipid uptake remains an almost unexplored research area. Although we know that long-chain bases (LCBs), constituents of sphingolipids, can enter into cells efficiently, the molecular mechanism of LCB uptake is completely unclear. Here, we found that the yeast acyl-CoA synthetases (ACSs) Faa1 and Faa4 are redundantly involved in LCB uptake. In addition to fatty acid-activating activity, transporter activity toward long-chain fatty acids (LCFAs) has been suggested for ACSs. Both LCB and LCFA transports were largely impaired in faa1Δ faa4Δ cells. Furthermore, LCB and LCFA uptakes were mutually competitive. However, the energy dependency was different for their transports. Sodium azide/2-deoxy-D-glucose treatment inhibited import of LCFA but not that of LCB. Furthermore, the ATP-AMP motif mutation FAA1 S271A largely impaired the metabolic activity and LCFA uptake, while leaving LCB import unaffected. These results indicate that only LCFA transport requires ATP. Since ACSs do not metabolize LCBs as substrates, Faa1 and Faa4 are likely directly involved in LCB transport. Furthermore, we revealed that ACSs are also involved in LCB transport in mammalian cells. Thus, our findings provide strong support for the hypothesis that ACSs directly transport LCFAs.
authors.affiliation: Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences, Hokkaido University, Kita 12-jo, Nishi 6-chome, Kita-ku, Sapporo 060-0812, Japan.
authors.forename: Tomomi
authors.initials: T
authors.lastname: Narita
authors.affiliation: Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences, Hokkaido University, Kita 12-jo, Nishi 6-chome, Kita-ku, Sapporo 060-0812, Japan.
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Naganuma
authors.affiliation: Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences, Hokkaido University, Kita 12-jo, Nishi 6-chome, Kita-ku, Sapporo 060-0812, Japan.
authors.forename: Yurie
authors.initials: Y
authors.lastname: Sase
authors.affiliation: Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences, Hokkaido University, Kita 12-jo, Nishi 6-chome, Kita-ku, Sapporo 060-0812, Japan.
authors.forename: Akio
authors.initials: A
authors.lastname: Kihara
mesh_terms: D000214:Acyl Coenzyme A / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport / Q000235:genetics; D003066:Coenzyme A Ligases / Q000235:genetics / Q000378:metabolism*; D005227:Fatty Acids / Q000235:genetics / Q000378:metabolism; D050356:Lipid Metabolism / Q000235:genetics; D008055:Lipids; D051381:Rats; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D013107:Sphingolipids / Q000235:genetics / Q000378:metabolism*
chemical_list: D000214:Acyl Coenzyme A; D005227:Fatty Acids; D008055:Lipids; D029701:Saccharomyces cerevisiae Proteins; D013107:Sphingolipids; D003066:Coenzyme A Ligases; C511244:Faa1 protein, S cerevisiae; C561832:Acsl1 protein, rat; C090206:FAA4 protein, S cerevisiae