AGAMOUS controls GIANT KILLER, a multifunctional chromatin modifier in reproductive organ patterning and differentiation

PLoS Biol. 2009 Nov;7(11):e1000251. doi: 10.1371/journal.pbio.1000251. Epub 2009 Nov 24.


The Arabidopsis homeotic protein AGAMOUS (AG), a MADS domain transcription factor, specifies reproductive organ identity during flower development. Using a binding assay and expression analysis, we identified a direct target of AG, GIANT KILLER (GIK), which fine-tunes the expression of multiple genes downstream of AG. The GIK protein contains an AT-hook DNA binding motif that is widely found in chromosomal proteins and that binds to nuclear matrix attachment regions of DNA elements. Overexpression and loss of function of GIK cause wide-ranging defects in patterning and differentiation of reproductive organs. GIK directly regulates the expression of several key transcriptional regulators, including ETTIN/AUXIN RESPONSE FACTOR 3 (ETT/ARF3) that patterns the gynoecium, by binding to the matrix attachment regions of target promoters. Overexpression of GIK causes a swift and dynamic change in repressive histone modification in the ETT promoter. We propose that GIK acts as a molecular node downstream of the homeotic protein AG, regulating patterning and differentiation of reproductive organs through chromatin organization.

Publication types

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

MeSH terms

  • AGAMOUS Protein, Arabidopsis / metabolism*
  • Arabidopsis / growth & development
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / metabolism*
  • Body Patterning*
  • Cell Nucleus / metabolism
  • Chromatin / metabolism
  • DNA-Binding Proteins / metabolism*
  • Flowers / growth & development*
  • Gene Expression Regulation, Plant*
  • Histones / metabolism
  • Matrix Attachment Regions
  • Nuclear Proteins / metabolism


  • AGAMOUS Protein, Arabidopsis
  • Arabidopsis Proteins
  • Chromatin
  • DNA-Binding Proteins
  • ETT protein, Arabidopsis
  • GIANT KILLER protein, Arabidopsis
  • Histones
  • Nuclear Proteins