Regulatory functions of nuclear hexokinase1 complex in glucose signaling

Cell. 2006 Nov 3;127(3):579-89. doi: 10.1016/j.cell.2006.09.028.

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Arabidopsis / enzymology
  • Arabidopsis / genetics
  • Arabidopsis / growth & development
  • Arabidopsis / metabolism
  • Cell Nucleus / enzymology
  • Gene Expression Regulation, Plant*
  • Glucose / metabolism*
  • Hexokinase / genetics
  • Hexokinase / isolation & purification
  • Hexokinase / metabolism*
  • Models, Biological
  • Nuclear Proteins / genetics
  • Nuclear Proteins / isolation & purification
  • Nuclear Proteins / metabolism*
  • Proteomics
  • Signal Transduction*

Substances

  • Nuclear Proteins
  • Hexokinase
  • Glucose