title: Molecular basis of sphingosine kinase 1 substrate recognition and catalysis.
abstract: Sphingosine kinase 1 (SphK1) is a lipid kinase that catalyzes the conversion of sphingosine to sphingosine-1-phosphate (S1P), which has been shown to play a role in lymphocyte trafficking, angiogenesis, and response to apoptotic stimuli. As a central enzyme in modulating the S1P levels in cells, SphK1 emerges as an important regulator for diverse cellular functions and a potential target for drug discovery. Here, we present the crystal structures of human SphK1 in the apo form and in complexes with a substrate sphingosine-like lipid, ADP, and an inhibitor at 2.0-2.3 Å resolution. The SphK1 structures reveal a two-domain architecture in which its catalytic site is located in the cleft between the two domains and a hydrophobic lipid-binding pocket is buried in the C-terminal domain. Comparative analysis of these structures with mutagenesis and kinetic studies provides insight into how SphK1 recognizes the lipid substrate and catalyzes ATP-dependent phosphorylation.
authors.affiliation: Department of Molecular Structure and Characterization, Amgen, Inc., 1120 Veterans Boulevard, South San Francisco, CA 94080, USA. zwang@amgen.com
authors.forename: Zhulun
authors.initials: Z
authors.lastname: Wang
authors.forename: Xiaoshan
authors.initials: X
authors.lastname: Min
authors.forename: Shou-Hua
authors.initials: SH
authors.lastname: Xiao
authors.forename: Sheree
authors.initials: S
authors.lastname: Johnstone
authors.forename: William
authors.initials: W
authors.lastname: Romanow
authors.forename: David
authors.initials: D
authors.lastname: Meininger
authors.forename: Haoda
authors.initials: H
authors.lastname: Xu
authors.forename: Jinsong
authors.initials: J
authors.lastname: Liu
authors.forename: Jessica
authors.initials: J
authors.lastname: Dai
authors.forename: Songzhu
authors.initials: S
authors.lastname: An
authors.forename: Stephen
authors.initials: S
authors.lastname: Thibault
authors.forename: Nigel
authors.initials: N
authors.lastname: Walker
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D002384:Catalysis; D018360:Crystallography, X-Ray; D006801:Humans; D007700:Kinetics; D008246:Lysophospholipids / Q000737:chemistry* / Q000378:metabolism; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011487:Protein Conformation; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D008246:Lysophospholipids; C060506:sphingosine 1-phosphate; D000255:Adenosine Triphosphate; D013110:Sphingosine