Structure-function analysis of the NB-ARC domain of plant disease resistance proteins

Gerben van Ooijen, Gabriele Mayr, Mobien M A Kasiem, Mario Albrecht, Ben J C Cornelissen, Frank L W Takken

Research output: Contribution to journalArticlepeer-review


Resistance (R) proteins in plants are involved in pathogen recognition and subsequent activation of innate immune responses. Most resistance proteins contain a central nucleotide-binding domain. This so-called NB-ARC domain consists of three subdomains: NB, ARC1, and ARC2. The NB-ARC domain is a functional ATPase domain, and its nucleotide-binding state is proposed to regulate activity of the R protein. A highly conserved methionine-histidine-aspartate (MHD) motif is present at the carboxy-terminus of ARC2. An extensive mutational analysis of the MHD motif in the R proteins I-2 and Mi-1 is reported. Several novel autoactivating mutations of the MHD invariant histidine and conserved aspartate were identified. The combination of MHD mutants with autoactivating hydrolysis mutants in the NB subdomain showed that the autoactivation phenotypes are not additive. This finding indicates an important regulatory role for the MHD motif in the control of R protein activity. To explain these observations, a three-dimensional model of the NB-ARC domain of I-2 was built, based on the APAF-1 template structure. The model was used to identify residues important for I-2 function. Substitution of the selected residues resulted in the expected distinct phenotypes. Based on the model, it is proposed that the MHD motif fulfils the same function as the sensor II motif found in AAA+ proteins (ATPases associated with diverse cellular activities)-co-ordination of the nucleotide and control of subdomain interactions. The presented 3D model provides a framework for the formulation of hypotheses on how mutations in the NB-ARC exert their effects.
Original languageEnglish
Pages (from-to)1383-1397
Number of pages15
JournalJournal of Experimental Botany
Issue number6
Publication statusPublished - 2008


  • Intramolecular interactions
  • MHD motif
  • NB-ARC domain
  • plant disease resistance
  • protein structure
  • R proteins
  • signal transduction
  • site-directed mutagenesis


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