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Phospho enol pyruvate carboxylase in mistletoe leaves: Regulation of gene expression, protein content, and covalent modification
Author(s) -
Li Xuemei,
Wanek Wolfgang,
Nehls U.,
Popp Marianne,
Hampp Rüdiger,
Rennenberg Heinz,
Einig Werner
Publication year - 2001
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1034/j.1399-3054.2001.1120307.x
Subject(s) - phosphoenolpyruvate carboxylase , biology , botany , photosynthesis , biochemistry
Seasonal changes in the activity of phospho enol pyruvate carboxylase (PEPCase, EC 4.1.1.31), a key enzyme in the interaction of carbohydrate and nitrogen metabolism, were studied in leaves of the C 3 semiparasitic mistletoe, Viscum album, growing on different host trees. Maximum extractable PEPCase activities were higher in leaves of mistletoes growing on Betula pendula and Alnus glutinosa hosts compared with those on the conifers, Abies alba and Larix decidua . Independent of host, maximum extractable PEPCase activities were high in spring and autumn while low in summer. Samples with higher PEPCase activities showed higher amounts of PEPCase protein and higher PEPCase mRNA levels. A curvilinear correlation between leaf total nitrogen content and the maximum extractable PEPCase activity as well as PEPCase mRNA level suggested that nitrogen might affect the activity of PEPCase of mistletoe by up‐regulating gene expression. In addition to extractable activity, seasonal changes of the PEPCase activation state, the ratio of activities resulting from limited:non‐limited assays, were found, which was correlated to the variation of malate content in leaves of mistletoe. ATP‐dependent activation of PEPCase was characterized by an increase in I 0.5 ( l ‐malate), indicating that PEPCase of leaves of mistletoes is probably regulated via phosphorylation.