Evidence for intracellular spatial separation of hexokinases and fructokinases in tomato plants.
Four hexokinase (LeHXK1-4) and four fructokinase (LeFRK1-4) genes were identified in tomato plants. Previous GFP fusion studies indicate that the gene product of LeHXK3 is associated with the mitochondria while that of LeHXK4 is located within plastids. In this study we found that the enzyme encoded by the fructokinase gene LeFRK3 is also located within plastids. The presence of LeFrk3 enzyme in plastids raises the question of the origin of fructose in these organelles. The other three FRKs enzymes, LeFrk1&2&4, are located in the cytosol. Unlike LeFrk1&2&4, the two additional HXKs, LeHxk1&2, share a common membrane anchor domain and are associated with the mitochondria similar to LeHxk3. The difference in the locations of the cytoplasmic FRK and HXK isozymes suggests that glucose phosphorylation is confined to defined special intracellular localizations while fructose phosphorylation is less confined.
Damari-Weissler
Hila
H
Institute of Plant Sciences, Agricultural Research Organization, The Volcani Center, Bet Dagan, 50250, Israel.
Kandel-Kfir
Michal
M
Gidoni
David
D
Mett
Anahit
A
Belausov
Eddy
E
Granot
David
D
D000595:Amino Acid Sequence; D001483:Base Sequence; D003600:Cytosol / Q000201:enzymology; D017931:DNA Primers; D018274:Electroporation; D005631:Fructokinases / Q000737:chemistry / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006593:Hexokinase / Q000737:chemistry / Q000378:metabolism*; D018551:Solanum lycopersicum / Q000201:enzymology*; D008969:Molecular Sequence Data; D018087:Plastids / Q000201:enzymology; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D017931:DNA Primers; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D005631:Fructokinases; D006593:Hexokinase