Abstract
In higher plants, various Z,E-mixed polyisoprenoids, including dolichol and polyprenol, are biosynthesized showing broad chain length distributions from C50 to C120. However, a physiological function of Z,E-mixed polyisoprenoids in higher plants is hardly elucidated. To understand physiological roles of Z,E-mixed polyisoprenoids, we are characterizing Arabidopsis thaliana cis-prenyltransferases (AtCPTs) which catalyze the formation of the basic backbone of Z,E-mixed polyisoprenoids. In this meeting, we report on the enzymatic characterization of AtCPT5.
AtCPT5 fused with a trigger factor as well as a histidine-tag was overexpressed in Escherichia coli and partially purified using Ni2+-affinity chromatography. AtCPT5 required Mg2+ for its CPT activity, in which optimal concentration was 1 mM. AtCPT5 was activated by the addition of Triton X-100. The optimal allylic substrate was farnesyl pyrophosphate (C15) among various allylic substrates (C5~C20). Analysis of the product chain length revealed that AtCPT5 had a novel medium-chain CPT activity, producing C35 polyisoprenoid as a major product.
