Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.1.1 (hexokinase)
 5,274 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In Arabidopsis (Arabidopsis thaliana), trehalose is present at almost undetectable levels, excluding its role as an osmoprotectant. Here, we report that overexpression of AtTPS1 in Arabidopsis using the 35S promoter led to a small increase in trehalose and trehalose-6-P levels. In spite of this, transgenic plants displayed a dehydration tolerance phenotype without any visible morphological alterations, except for delayed flowering. Moreover, seedlings overexpressing AtTPS1 exhibited glucose (Glc)- and abscisic acid (ABA)-insensitive phenotypes. Transgenic seedlings germinated on Glc were visibly larger with green well-expanded cotyledonary leaves and fully developed roots, in contrast with wild-type seedlings showing growth retardation and absence of photosynthetic tissue. An ABA dose-response experiment revealed a higher germination rate for transgenic plants overexpressing AtTPS1 showing insensitive germination kinetics at 2.5 mum ABA. Interestingly, germination in the presence of Glc did not trigger an increase in ABA content in plants overexpressing AtTPS1. Expression analysis by quantitative reverse transcription-PCR in transgenic plants showed up-regulation of the ABI4 and CAB1 genes. In the presence of Glc, CAB1 expression remained high, whereas ABI4, HXK1, and ApL3 levels were down-regulated in the AtTPS1-overexpressing lines. Analysis of AtTPS1 expression in HXK1-antisense or HXK1-sense transgenic lines suggests the possible involvement of AtTPS1 in the hexokinase-dependent Glc-signaling pathway. These data strongly suggest that AtTPS1 has a pivotal role in the regulation of Glc and ABA signaling during vegetative development.
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PMID:The Arabidopsis trehalose-6-P synthase AtTPS1 gene is a regulator of glucose, abscisic acid, and stress signaling. 1749 18

Unlike Arabidopsis hexokinase (AtHXK) 1, cyanobacterial glucokinase (cGlk, Sll0593) from Synechocystis sp. PCC6803 does not function endogenously as a glucose sensor for glucose repression of photosynthesis-related genes such as psbA2, psbD2, rbcS, and rbcL. However, when cGlk was constitutively expressed in the cytosol of the glucose insensitive AtHXK 1 null mutant gin2-1, transgenic plants showed glucose sensitive phenotypes similar to those of wild type plants, namely glucose-induced decreases in Chl content and transcript levels of genes encoding Chl binding proteins (CAB1) and Rubisco small subunit (RBCS). Therefore, we suggest that cGlk's ability to complement glucose sensing activity in higher plants is attributable to the presence of cGlk-interacting proteins present in Arabidopsis, but absent in Synechocystis.
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PMID:Cyanobacterial glucokinase complements the glucose sensing role of Arabidopsis thaliana hexokinase 1. 1864 98