Cho, Young-Hee , Yoo, Sang-Dong , Sheen, Jen .
Nuclear Glucose Signaling through Hexokinase1 and HUPs in Arabidopsis.
Arabidopsis hexokinase1 (HXK1) is a glucose sensor that integrates nutrient and hormone signals to govern gene expression and plant growth in response to environmental cues. How the metabolic enzyme mediates glucose signaling remains a mystery. By coupling proteomic and binary-interaction screens, we discover two nuclear-specific HXK1 unconventional partners (HUPs). Surprisingly, HUP1 and HUP2 also have evolutionarily conserved biochemical functions in other protein complexes, the vacuolar H+-ATPase and the 19S regulatory particle of proteasome. Remarkably, hup1 and hup2 mutants uniquely share a broad spectrum of glucose response defects with the HXK1 mutant gin2 (glucose-insensitive2). Genetic and chromatin immunoprecipitation analyses suggest that the nuclear HXK1 and HUPs form a glucose sensing/signaling complex core and directly modulate specific target gene transcription independent of glucose metabolism. The findings support novel concepts that ancient and conserved enzymes/proteins of well-established activities may perform previously unrecognized functions with different partners in distinct cellular compartments and signaling pathways. (This work is supported by the NIH GM60493 and the NSF IBN-0217191).
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Regulatory functions of Nuclear HXK1 complex in glucose signaling
1 - MGH/Harvard University, Molecular Biology, 185 Cambridge St, Boston, MA, 02114, USA
2 - MGH/Harvard University, Molecular biology
nuclear HXK1 complex
HXK1 unconventional partner.
Presentation Type: ASPB Minisymposium
Location: International Ballroom South/Hilton
Date: Wednesday, July 11th, 2007
Time: 10:40 AM