A lipid binding domain in sphingosine kinase 2.
The lipid second messenger sphingosine 1-phosphate (S1P) is a critical mediator of cellular proliferation and survival signals, and is essential for vasculogenesis and neurogenesis. S1P formation is catalysed by sphingosine kinases 1 and 2 (Sphk1 and Sphk2). We have found that the endogenous glycolipid sulfatide (3-O-sulfogalactosylceramide) binds to and inhibits the activity of Sphk2 and the closely related ceramide kinase (Cerk), but not Sphk1. Using sulfatide as a probe, we mapped the lipid binding domain to the N-terminus of Sphk2 (residues 1-175), a region of sequence that is absent in Sphk1, but aligns with a pleckstrin homology domain in Cerk. Accordingly, Sphk2 bound to phosphatidylinositol monophosphates but not to abundant cellular phospholipids. Deleting the N-terminal domain reduced Sphk2 membrane localisation in cells. We have therefore identified a lipid binding domain in Sphk2 that is important for the enzyme's sub-cellular localisation.
Don
Anthony S
AS
Cancer Research Centre, Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia.
Rosen
Hugh
H
D020134:Catalytic Domain; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism*; D006801:Humans; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D013433:Sulfoglycosphingolipids / Q000494:pharmacology; D000099157:Sphingosine Kinase
D018129:Phosphatidylinositol Phosphates; D017853:Phosphotransferases (Alcohol Group Acceptor); D013433:Sulfoglycosphingolipids; D000099157:Sphingosine Kinase; C066324:ceramide kinase