title: Regulatory functions of nuclear hexokinase1 complex in glucose signaling.
abstract: 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: the vacuolar H(+)-ATPase B1 (VHA-B1) and the 19S regulatory particle of proteasome subunit (RPT5B). Remarkably, vha-B1 and rpt5b 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 forms a glucose signaling complex core with VHA-B1 and RPT5B that directly modulates specific target gene transcription independent of glucose metabolism. The findings support a model in which conserved metabolic enzymes and proteins of well-established activities may perform previously unrecognized nuclear functions.
authors.affiliation: Department of Molecular Biology, Massachusetts General Hospital, Department of Genetics, Harvard Medical School, Boston, MA 02114, USA.
authors.forename: Young-Hee
authors.initials: YH
authors.lastname: Cho
authors.forename: Sang-Dong
authors.initials: SD
authors.lastname: Yoo
authors.forename: Jen
authors.initials: J
authors.lastname: Sheen
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D002467:Cell Nucleus / Q000201:enzymology; D018506:Gene Expression Regulation, Plant; D005947:Glucose / Q000378:metabolism*; D006593:Hexokinase / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D008954:Models, Biological; D009687:Nuclear Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D040901:Proteomics; D015398:Signal Transduction
chemical_list: D009687:Nuclear Proteins; D006593:Hexokinase; D005947:Glucose