Studies of Functional Conversion of Prenyltransferase

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1. We introduced site-directed mutageneses in farnesyl diphosphate synthase, which yields C_<15> product, to change the chain length of its product. The amino acid residues proximate to the first aspartate rich motif, which is involved in substrate-binding, were substituted according to previous information. Consequently, we succeeded in altering the property of the enzyme and in creating the mutant enzyme which yields C_<10> product, geranyl diphosphate. The result supports our hypothesis on the mechanism of product chain length determination of prenyltransferase. Besides, the mutant might be applied in industrial use because geranyl diphosphate is the precursor of monoterpenes.2. We introduced site-directed mutageneses in heptaprenyl diphosphate synthase, which yields C_<35> product, according to previous information. We succeeded in changing it to the mutant enzymes that yield shorter or longer products. Heptaprenyl diphosphate synthase is classified into medium-chain prenyltransferase based on the difference of quaternary structure. The result of our studies revealed that medium-chain prenyltransferase also shares the mechanism of product chain length determination common to prenyltransferases.3. As new targets for changing the enzymatic properties, we cloned the genes of several novel prenyltransferases, including the one which has the product specificity that has never known. Elucidation of their enzymatic mechanism and change of their properties would give us useful knowledge for the research of prenyltransferase. Besides, they might also provide us information about the thermostability of enzymes because all of the cloned enzymes are derived from thermophilic microorganisms and are thermostable.