41 植物の低温馴化とリン脂質生合成

概要

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CTP : phosphoethanolamine citidylyltransferase (ECT) is a key enzyme in the CDP-ethanolamine pathway for phosphatidylethanolamine (PE) synthesis. A cDNA clone for ECT, WECT1,was isolated from wheat after screening a macroarrayed cDNA library for genes that are induced during cold acclimation (CA). WECT1 encodes for a putative 46.7kD polypeptide that exhibits 43% and 34% identity with hET from human and ECT1 from S. cerevisiae, respectively. A GST-WECT1 fusion protein was produced in E. coli as a soluble protein. The crude extract from the cells producing GST-WECT1 exhibited an ECT activity, while E. coli cells with the vector plasmid did not show detectable activity. The WECT1 mRNA accumulated in crown tissue of wheat during CA, suggesting involvement of PE in the CA process. Measurement of leaf PE contents revealed that PE levels were increased by 54% during 14 days of CA. In contrast, increase in the phosphatidylcholine (PC) contents was only 12%. Measurement of fatty acid contents in both PE and PC fractions revealed that change in fatty acid composition during CA was minor. Collectively these data suggest that enhanced expression of WECT1 is involved in the adaptation of membrane phospholipid to low temperature by increasing the PE/PC ratio.
植物化学調節学会の論文
2002-10-31