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Increased glutamine synthetase activity and changes in amino acid pools in leaves treated with 5‐aminoimidazole‐4‐carboxiamide ribonucleoside (AICAR)
Author(s) -
Man HuiMin,
Kaiser Werner M.
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.1399-3054.2001.1110305.x
Subject(s) - glutamine synthetase , glycine , ribonucleoside , biochemistry , glutamine , serine , amino acid , nitrate reductase , ammonium , biology , enzyme , chemistry , rna , organic chemistry , gene
Feeding 5‐aminoimidazole‐4‐carboxiamide ribonucleoside (AICAR) through the petiole of detached young barley leaves rapidly increased activities of NADH‐nitrate reductase (NR) and glutamine synthetase (GS) in leaf extracts and at least partly prevented the usual slow decrease of these enzyme activities during prolonged illumination. Further, AICAR caused drastic changes in amino acid levels: glutamine and serine levels were increased whereas glutamate and glycine were decreased, probably indicating a higher GS activity and more rapid conversion of glycine into serine. The latter may be responsible for the higher ammonium contents found in AICAR treated leaves. We tentatively suggest that GS (located in the chloroplast) and glycine decarboxylase (located in the mitochondria) are regulated in a manner similar to NR. This is discussed in the light of recent reports that 14‐3‐3 isoforms exist in chloroplasts and that GS binds to 14‐3‐3s in vitro.