title: Sweet sensor, surprising partners.
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.
authors.affiliation: Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada. jingui@interchange.ubc.ca
authors.forename: Jin-Gui
authors.initials: JG
authors.lastname: Chen
mesh_terms: D002467:Cell Nucleus / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D006593:Hexokinase / Q000378:metabolism; D008954:Models, Biological; D010940:Plant Proteins / Q000378:metabolism; D011485:Protein Binding; D015398:Signal Transduction
chemical_list: D010940:Plant Proteins; D006593:Hexokinase; D005947:Glucose