Glucose inhibits the expression of triose phosphate/phosphate translocator gene in wheat via hexokinase-dependent mechanism.
Although triose phosphate/phosphate translocator is known to play an important role in regulating the distribution of assimilates in wheat chloroplasts, the mechanism of triose phosphate/phosphate translocator gene control has not yet been clearly elucidated. We first showed that glucose inhibited the expression of triose phosphate/phosphate translocator gene in wheat by reverse transcription-polymerase chain reaction and Western blotting. The triose phosphate/phosphate translocator expression was seriously impaired by 5 mmol/L glucose, and it responded slowly, more than 48 h, to level as low as 1 mmol/L glucose. Both glucose and 2-deoxyglucose inhibited the expression of triose phosphate/phosphate translocator gene, but 2-deoxyglucose-6-P, product of phosphorylated 2-deoxyglucose, cannot be further metabolized, therefore the further metabolism of phosphorylated glucose by hexokinase is not a prerequisite for triggering glucose-regulated expression of triose phosphate/phosphate translocator gene. Glucose had little inhibitory effect on the expression of triose phosphate/phosphate translocator gene when hexokinase activity was reduced or eliminated by transforming wheat protoplasts with a hexokinase antisense construct or treating protoplasts with glucosamine, an inhibitor of hexokinase. Therefore, it appears essential for hexokinase to retain phosphorylation activity for glucose to regulate the expression of triose phosphate/phosphate translocator gene. The treatment of protoplasts with glucose-6-phosphate resulting in no inhibition of triose phosphate/phosphate translocator expression demonstrated that phosphorylation via hexokinase is necessary for glucose inhibiting triose phosphate/phosphate translocator expression. All the data suggest that triose phosphate/phosphate translocator is regulated by glucose via a hexokinase-dependent pathway.
Sun
Jin-Yue
JY
College of Biological Sciences, China Agricultural University, The State Key Laboratory for Plant Physiology and Biochemistry, Beijing 100094, PR China.
Chen
Ye-Miao
YM
Wang
Qing-Mei
QM
Chen
Jia
J
Wang
Xue-Chen
XC
D060365:Chloroplast Proteins; D015536:Down-Regulation / Q000187:drug effects*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D005947:Glucose / Q000378:metabolism / Q000494:pharmacology*; D006593:Hexokinase / Q000235:genetics / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000032:analysis / Q000187:drug effects / Q000235:genetics*; D010940:Plant Proteins / Q000032:analysis / Q000187:drug effects / Q000235:genetics*; D015398:Signal Transduction; D014908:Triticum / Q000235:genetics* / Q000378:metabolism
D060365:Chloroplast Proteins; D026901:Membrane Transport Proteins; D010940:Plant Proteins; D006593:Hexokinase; D005947:Glucose