Human sphingosine-1-phosphate lyase: cDNA cloning, functional expression studies and mapping to chromosome 10q22

Sphingosine-1-phosphate lyase catalyzes the last step in sphingolipid break down, the cleavage of phosphorylated sphingoid bases such as sphingenine-1- phosphate. The latter lipid is not only a catabolite, but can influence as an inter- and/or intracellular second messenger many cellular processes. To allow for the diagnosis of human disorders that might be linked to a defic ient lyase, the human sphingosine-l-phosphate lyase cDNA was cloned. The ob tained cDNA encoded a protein of 568 amino acids with a calculated molecula r mass of 63 492 Da. Hydropathy plots revealed the presence of one membrane span near the amino-terminal which is however not required for enzyme acti vity since recombinant poly-His-tagged lyase, lacking this membrane span, w as functionally active. Site-directed mutagenesis disclosed the importance of the cysteine residues 218 and 317 for the cleavage reaction. Northern an alysis showed the presence of rare large-sized mRNAs of 6.7, 5.8 and 4 kb a nd the highest expression in liver. By fluorescent in situ hybridization, t he gene was mapped to chromosome 10q22. (C) 2000 Elsevier Science B.V. All rights reserved.