スフィンゴ脂質生合成を律速するセリンパルミトイル転移酵素の研究

概要

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Serine palmitoyltransferase (SPT) is a key enzyme of sphingolipid biosynthesis and catalyzes the decarboxylative condensation of L-serine with palmitoyl-CoA to form 3-ketodihydrosphingosine. Eukaryote SPTs are known as heterodimers composed of tightly membrane-bound subunits, which makes their detailed analysis difficult. Therefore, as the alternative enzyme source, we focused into the bacteria that contain a large amount of sphingolipid as their cellular component. We have purified a water-soluble homodimeric SPT from Sphingomonas paucimobilis 2395^T first, then cloned SPT genes from several bacterial species and have overproduced them in E. coli. Using these bacterial enzymes, the reaction mechanism of SPT was analyzed in detail and X-ray crystallographic analysis of its structure in a complex with the amino acid substrate, L-serine were performed. These results allow us to understand the structure-function relationship of eukaryote SPT.
2008-02-25