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Sci. STKE, 13 February 2007
Vol. 2007, Issue 373, p. pe7
[DOI: 10.1126/stke.3732007pe7]


Sweet Sensor, Surprising Partners

Jin-Gui Chen*

Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.

Abstract: Hexokinase1 (HXK1) is an evolutionarily conserved glucose sensor in plants. However, the molecular mechanism through which HXK1 controls the expression of genes encoding proteins involved in photosynthesis is a mystery. Recent research demonstrates that a previously unknown HXK1 nuclear complex controls the expression of specific photosynthetic genes, a process that is independent of glucose metabolism but requires two unexpected partners, VHA-B1 and RPT5B. Both VHA-B1 and RPT5B have well-established and conserved functions in processes that are seemingly unrelated to glucose-dependent regulation of gene expression, and neither of them is a predominantly nuclear protein. Biochemical, genetic, and molecular evidence demonstrates that VHA-B1 and RPT5B directly interact with HXK1 in the nucleus and that the HXK1 complex binds to the cis-acting elements of chlorophyll a/b binding protein 2, a photosynthetic gene that is transcriptionally suppressed by glucose. The identification of the HXK1 nuclear complex reveals an unexpected glucose-signaling mechanism and reinforces the notion that metabolic enzymes can play unique roles in signal transduction by directly controlling gene expression in the nucleus.

Corresponding author. E-mail: jingui{at}

Citation: J.-G. Chen, Sweet Sensor, Surprising Partners. Sci. STKE 2007, pe7 (2007).

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Role of the Rice Hexokinases OsHXK5 and OsHXK6 as Glucose Sensors.
J.-I. Cho, N. Ryoo, J.-S. Eom, D.-W. Lee, H.-B. Kim, S.-W. Jeong, Y.-H. Lee, Y.-K. Kwon, M.-H. Cho, S. H. Bhoo, et al. (2009)
Plant Physiology 149, 745-759
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