High impact information on ATHXK1

• The characterization of the gin5 mutant, on the other hand, reveals that glucose-specific accumulation of ABA is essential for hexokinase-mediated glucose responses [1].
• VIGS of Hxk1 reduced the cellular glucose-phosphorylating activity to approximately 31% of control levels without changing the fructose-phosphorylating activity and did not alter hexose phosphate content severely [2].
• Hxk1 was associated with the mitochondria, and this association required the N-terminal membrane anchor [2].
• Recent findings suggest a pivotal role for mitochondria-associated hexokinase in the regulation of apoptosis in animal cells [2].
• In this study, virus-induced gene silencing (VIGS) of a hexokinase-encoding Hxk1 caused necrotic lesions on leaves, abnormal leaf morphology, and retarded plant growth in Nicotiana benthamiana [2].

Biological context of ATHXK1

• In addition, the transgenic plants underwent rapid senescence, suggesting that hexokinase is also involved in senescence regulation [3].
• Regulation of root ion transporters by photosynthesis: functional importance and relation with hexokinase [4].
• Sugar induced cell death in yeast is dependent on the rate of sugar phosphorylation as determined by Arabidopsis thaliana hexokinase [5].
• The molecular details of sugar sensing and sugar-mediated signal transduction pathways are unclear but recent results suggest that hexokinase functions as an important plant sugar sensor in a way that is similar to that found in yeast [6].
• Suppression of din gene expression by 2-deoxy-Glc, and a non-suppressive effect exerted by 3-O-methyl-Glc, suggested that sugar-repressible expression of din genes is mediated through the phosphorylation of hexose by hexokinase, as exemplified in the repression of photosynthetic genes by sugars [7].

Anatomical context of ATHXK1

• Finally, the addition of recombinant Hxk1 to mitochondria-enriched fractions prevented H(2)O(2)/clotrimazole-induced cytochrome c release and loss of mitochondrial membrane potential [2].
• The in vitro activities of hexokinase, vacuolar acid invertase, and cell wall acid invertase do not change until the late stages of senescence, when they increase markedly [8].

Associations of ATHXK1 with chemical compounds

• These results indicate that the induction of AtNrt2.1 expression by sugars is unrelated to the main signaling mechanisms documented for sugar sensing in plants, such as regulation by sucrose, hexose transport, and hexokinase (HXK) sensing activity [4].
• Furthermore, based on flow cytometry, Arabidopsis thaliana plants overexpressing Arabidopsis HXK1 and HXK2, both of which are predominantly associated with mitochondria, exhibited enhanced resistance to H(2)O(2)- and alpha-picolinic acid-induced PCD [2].
• In plants, 3-o-methylglucose is phosphorylated by hexokinase but not perceived as a sugar [9].
• Carbohydrate-mediated regulation of gene expression involving a HXK-mediated pathway is known to be activated by Glc, Man, and other monosaccharides [10].
• Our analysis suggests the involvement of abscisic acid and components of the abscisic acid signal transduction cascade in a hexokinase-dependent sugar response pathway [11].

Regulatory relationships of ATHXK1

• By contrast, the stimulation of LKR/SDH protein expression by sugar starvation is regulated by the hexokinase-signaling cascade in a similar manner to the repression of many photosynthetic genes by sugars [12].

Other interactions of ATHXK1

• Here we show that glucose enhances the degradation of ETHYLENE-INSENSITIVE3 (EIN3), a key transcriptional regulator in ethylene signalling, through the plant glucose sensor hexokinase [13].
• Because the activities of several glycolytic enzymes, in particular hexokinase and pyrophosphate-dependent phosphofructokinase, are reduced in developing homozygous wri1 seeds, it is suggested that WRI1 is involved in the developmental regulation of carbohydrate metabolism during seed filling [14].
• Here we show that the ABI4 transcription factor mediates the effects of trehalose on starch metabolism and growth, independently of abscisic acid (ABA) synthesis and hexokinase (HXK1) signaling [15].
• However, T-6-P is not an inhibitor of AtHXK1 or AtHXK2 [16].
• Sucrose and light regulation of a cold-inducible UDP-glucose pyrophosphorylase gene via a hexokinase-independent and abscisic acid-insensitive pathway in Arabidopsis [17].

Analytical, diagnostic and therapeutic context of ATHXK1

• We have cloned a hexokinase gene, PpHXK1, in the moss Physcomitrella patens where gene function can be studied directly by gene targeting [18].

References