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Isolation and functional characterization of a novel plastidic hexokinase from Nicotiana tabacum
Author(s) -
Giese Jens-Otto,
Herbers Karin,
Hoffmann Manuela,
Klösgen Ralf Bernd,
Sonnewald Uwe
Publication year - 2005
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2004.12.071
Subject(s) - hexokinase , chloroplast , nicotiana tabacum , biochemistry , guard cell , biology , xylem , starch , c4 photosynthesis , sugar , plant cell , glucokinase , enzyme , botany , glycolysis , gene
Due to their central role in sugar metabolism and signalling plant hexokinases have been studied in great detail, however, little is known about the spatial and temporal expression and the sub‐cellular distribution of individual hexokinase isoforms. Based on in planta and in vitro studies the recently isolated tobacco hexokinase 2 (Hxk2) could be located in the chloroplast stroma and biochemically characterized. Hxk2 represents the first innerplastidic hexokinase described from higher plants. Promoter studies indicate that Hxk2 is mainly expressed in cells of the vascular starch sheath and xylem parenchyma, in guard cells and root tips. We propose a role for Hxk2 in starch and secondary metabolism in the mentioned tissues.