Senescence-associated Barley NAC (NAM, ATAF1,2, CUC) Transcription Factor Interacts with Radical-induced Cell Death 1 through a Disordered Regulatory Domain

Trine Kjaersgaard, Michael Krogh Jensen, Michael Christiansen, Per L. Gregersen, Birthe Brandt Kragelund, Karen Skriver

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Senescence in plants involves massive nutrient relocation and age-related cell death. Characterization of the molecular components, such as transcription factors (TFs), involved in these processes is required to understand senescence. We found that HvNAC005 and HvNAC013 of the plant-specific NAC (NAM, ATAF1,2, CUC) TF family are up-regulated during senescence in barley (Hordeum vulgare). Both HvNAC005 and HvNAC013 bound the conserved NAC DNA target sequence. Computational and biophysical analyses showed that both proteins are intrinsically disordered in their large C-terminal domains, which are transcription regulatory domains (TRDs) in many NAC TFs. Using motif searches and interaction studies in yeast we identified an evolutionarily conserved sequence, the LP motif, in the TRD of HvNAC013. This motif was sufficient for transcriptional activity. In contrast, HvNAC005 did not function as a transcriptional activator suggesting that an involvement of HvNAC013 and HvNAC005 in senescence will be different. HvNAC013 interacted with barley radical-induced cell death 1 (RCD1) via the very C-terminal part of its TRD, outside of the region containing the LP motif. No significant secondary structure was induced in the HvNAC013 TRD upon interaction with RCD1. RCD1 also interacted with regions dominated by intrinsic disorder in TFs of the MYB and basic helix-loop-helix families. We propose that RCD1 is a regulatory protein capable of interacting with many different TFs by exploiting their intrinsic disorder. In addition, we present the first structural characterization of NAC C-terminal domains and relate intrinsic disorder and sequence motifs to activity and protein-protein interactions.
Original languageEnglish
JournalJournal of Biological Chemistry
Issue number41
Pages (from-to)35418-35429
Publication statusPublished - 2011
Externally publishedYes


  • age-related cell death
  • protein-protein interaction
  • senescence
  • Monocotyledones Angiospermae Spermatophyta Plantae (Angiosperms, Monocots, Plants, Spermatophytes, Vascular Plants) - Gramineae [25305] Hordeum vulgare species barley common
  • Plantae (Fungi, Microorganisms, Nonvascular Plants, Plants) - Fungi [15000] yeast common
  • Hordeum vulgare HvNAC005 gene [Gramineae]
  • Hordeum vulgare HvNAC013 gene [Gramineae]
  • DNA
  • NAC
  • transcription factor
  • 03502, Genetics - General
  • 03504, Genetics - Plant
  • 10062, Biochemistry studies - Nucleic acids, purines and pyrimidines
  • 24500, Gerontology
  • Biochemistry and Molecular Biophysics
  • AK251058 GenBank, EMBL, DDJB nucleotide sequence
  • AK376297.1 GenBank, EMBL, DDJB nucleotide sequence
  • FR846236 GenBank, EMBL, DDJB nucleotide sequence
  • Aging
  • Molecular Genetics


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