Abstract Detail

Recent Topics Posters

Schreiber, Karl [1], Staskawicz, Brian [1].

Intermolecular interactions facilitate cell death induction by the Arabidopsis immune receptor RPP1.

Through interactions with various phytopathogens, plants have evolved disease resistance (R) proteins that recognize pathogen virulence effector proteins and induce strong immune responses, including host cell death.  These R proteins are generally modular in structure, with an N-terminal coiled-coil or Toll/Interleukin-1 Receptor (TIR) domain followed by a nucleotide-binding (NB) domain, and terminating in a leucine-rich repeat region.  Despite the critical role of R proteins in immunity, the mechanisms by which these receptors detect pathogen effectors and stimulate plant defenses remain poorly understood.  In Arabidopsis, the R protein RPP1 (Resistance to Peronsopora parasitica 1) recognizes the effector protein ATR1 (Arabidopsis thaliana Recognized 1) from the oomycete pathogen Hyaloperonospora arabidopsidis.  In this study, we sought to functionally characterize the domains of RPP1 with regards to cell death induction following effector recognition.  Interestingly, expression of the TIR domain alone induced cell death in the absence of ATR1, and we used allelic variation in TIR sequences to define key residues that contribute to this phenotype.  For some alleles, TIR autoactivity required the inclusion of the NB domain plus a C-terminal subdomain that is also found in Apaf-1, other R-proteins, and CED-4 (ARC1).  Co-immunoprecipitation experiments indicated that this NB-ARC1 region could self-associate in planta.  Importantly, we observed effector-dependent self-association of full-length RPP1, and used targeted mutagenesis to show that the NB domain is one of the primary drivers of oligomerization following recognition of an effector.  Based on these and other biochemical analyses, a model of RPP1 activation will be discussed.

1 - University of California, Berkeley, Plant & Microbial Biology, 241 Koshland Hall, Berkeley, CA, 94720, USA

Keywords:
Resistance proteins
protein-protein interactions
immune response regulation.

Presentation Type: Recent Topics Poster
Session: P
Location: Hall D/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 5:30 PM
Number: PRT031
Abstract ID:1815
Candidate for Awards:None