title: The mechanism of membrane targeting of human sphingosine kinase 1.
abstract: Sphingosine 1-phosphate is a bioactive sphingolipid that regulates cell growth and suppresses programmed cell death. The biosynthesis of sphingosine 1-phosphate is catalyzed by sphingosine kinase (SK) but the mechanism by which the subcellular localization and activity of SK is regulated in response to various stimuli is not fully understood. To elucidate the origin and structural determinant of the specific subcellular localization of SK, we performed biophysical and cell studies of human SK1 (hSK1) and selected mutants. In vitro measurements showed that hSK1 selectively bound phosphatidylserine over other anionic phospholipids and strongly preferred the plasma membrane-mimicking membrane to other cellular membrane mimetics. Mutational analysis indicates that conserved Thr54 and Asn89 in the putative membrane-binding surface are essential for lipid selectivity and membrane targeting both in vitro and in the cell. Also, phosphorylation of Ser225 enhances the membrane affinity and plasma membrane selectivity of hSK1, presumably by modulating the interaction of Thr54 and Asn89 with the membrane. Collectively, these studies suggest that the specific plasma membrane localization and activation of SK1 is mediated largely by specific lipid-protein interactions.
authors.affiliation: Department of Chemistry, University of Illinois, Chicago, Illinois 60607, USA.
authors.forename: Robert V
authors.initials: RV
authors.lastname: Stahelin
authors.forename: Jeong H
authors.initials: JH
authors.lastname: Hwang
authors.forename: Jin-Hahn
authors.initials: JH
authors.lastname: Kim
authors.forename: Zee-Yong
authors.initials: ZY
authors.lastname: Park
authors.forename: Korey R
authors.initials: KR
authors.lastname: Johnson
authors.forename: Lina M
authors.initials: LM
authors.lastname: Obeid
authors.forename: Wonhwa
authors.initials: W
authors.lastname: Cho
mesh_terms: D000595:Amino Acid Sequence; D001216:Asparagine / Q000737:chemistry; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism*; D004252:DNA Mutational Analysis; D049452:Green Fluorescent Proteins / Q000737:chemistry; D006801:Humans; D007700:Kinetics; D008055:Lipids / Q000737:chemistry; D008246:Lysophospholipids / Q000737:chemistry; D013058:Mass Spectrometry; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation; D010455:Peptides / Q000737:chemistry; D010713:Phosphatidylcholines / Q000737:chemistry; D010714:Phosphatidylethanolamines / Q000737:chemistry; D010718:Phosphatidylserines / Q000737:chemistry; D010743:Phospholipids / Q000737:chemistry; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D011312:Pressure; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D012694:Serine / Q000737:chemistry; D013110:Sphingosine / Q000031:analogs & derivatives / Q000737:chemistry; D020349:Surface Plasmon Resonance; D013912:Threonine / Q000737:chemistry; D013997:Time Factors; D014162:Transfection; D000099157:Sphingosine Kinase
chemical_list: D001216:Asparagine; D049452:Green Fluorescent Proteins; D008055:Lipids; D008246:Lysophospholipids; D010455:Peptides; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010718:Phosphatidylserines; D010743:Phospholipids; D017853:Phosphotransferases (Alcohol Group Acceptor); D012694:Serine; D013110:Sphingosine; D013912:Threonine; D000099157:Sphingosine Kinase; C057561:1-palmitoyl-2-oleoylphosphatidylethanolamine; C060506:sphingosine 1-phosphate; C028694:1-palmitoyl-2-oleoylphosphatidylcholine