CLONING AND EXPRESSION ANALYSIS OF THE CYTOSOLIC NADP(+)-DEPENDENT ISOCITRATE DEHYDROGENASE FROM POTATO - IMPLICATIONS FOR NITROGEN-METABOLISM

被引:84
作者
FIEUW, S
MULLERROBER, B
GALVEZ, S
WILLMITZER, L
机构
[1] INST GENBIOL FORSCH BERLIN GMBH, D-14195 BERLIN, GERMANY
[2] UNIV PARIS 11, CNRS, URA D1128, F-91405 ORSAY, FRANCE
关键词
D O I
10.1104/pp.107.3.905
中图分类号
Q94 [植物学];
学科分类号
071001 ;
摘要
A full-length cDNA (icdh-1) encoding a cytosolic NADP(+)-dependent isocitrate dehydrogenase (ICDH-1) from potato (Solanum tuberosum L.) has been isolated. Analysis of the deduced protein sequence revealed considerable homologies with the corresponding proteins from other eukaryotes such as tobacco, alfalfa, soybean, cattle, pig, and yeast. The gene was transcribed in all tissues tested, with the highest amount of icdh-1 transcript being found in green tissues, in flowers, and in roots. In leaves, enzyme activities were dependent on the age, with fully mature leaves showing the highest level of RNA expression and enzyme activity. This observation may indicate that NADP(+)-dependent ICDH is not only involved in amino acid biosynthesis via the glutamine synthetase/glutamine oxoglutarate aminotransferase cycle but also in cycling, redistribution, and export of amino acids. The latter assumption has been strengthened by our finding of a preferential expression of NADP(+)-dependent ICDH in leaf veins. Under in vivo conditions, the expression pattern paralleled the enzyme activity, indicating coarse control on the RNA level. Experiments carried out with detached leaves revealed an influence of light, nitrate, and sucrose on icdh-1 transcript levels and in some cases also on NADP(+)-dependent ICDH activity. In darkness, nitrate or sucrose induced icdh-1 mRNA expression. Leaves kept under starvation conditions exhibited a decrease of their protein content, whereas icdh-1 expression and ICDH activity increased significantly.
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页码:905 / 913
页数:9
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