Disease relevance of RIN4

• Regulation of R protein-mediated signaling in response to the bacterial pathogen Pseudomonas syringae in Arabidopsis involves the physical association of at least two R proteins with the negative regulator RPM1 INTERACTING PROTEIN4 (RIN4) [1].

High impact information on RIN4

• The R proteins, RPS2 and RPM1, sense type III effector-induced perturbations of RIN4 [2].
• RIN4 is an Arabidopsis protein targeted by AvrRpt2 and AvrRpm1 for degradation and phosphorylation, respectively [2].
• Initiation of RPS2-specified disease resistance in Arabidopsis is coupled to the AvrRpt2-directed elimination of RIN4 [3].
• We suggest that RIN4 is the target of the AvrRpt2 virulence function, and that perturbation of RIN4 activates RPS2 [4].
• RIN4 overexpression inhibits multiple phenotypes associated with AvrRpt2 function [4].

Biological context of RIN4

• NDR1 Interaction with RIN4 Mediates the Differential Activation of Multiple Disease Resistance Pathways in Arabidopsis [1].
• In fact, RIN4 negatively regulates AvrRpt2 virulence function [5].
• One or more of three consecutive cysteines in this C-terminal fragment are required for RIN4 localization; these are likely to be palmitoylation and/or prenylation sites [6].
• AvrRpm1 and AvrB induce RIN4 phosphorylation [7].
• RIN4 reduction results in heightened resistance to virulent Peronospora parasitica and P. syringae, and ectopic defense gene expression [7].

Anatomical context of RIN4

• The Pseudomonas syringae effector AvrRpt2 cleaves its C-terminally acylated target, RIN4, from Arabidopsis membranes to block RPM1 activation [6].
• Plasma-membrane localization of RIN4 was not affected by AvrRpml [8].

Associations of RIN4 with chemical compounds

• The type III effector AvrRpt2 is a cysteine protease that is autoprocessed inside the host cell where it activates RPS2 by causing RIN4 disappearance [6].
• In addition to negatively regulating RPS2 activity, RIN4 is also a target of AvrRpt2, a Cys protease and cognate bacterial effector protein of RPS2 [9].

Physical interactions of RIN4

• RIN4 interacts with Pseudomonas syringae type III effector molecules and is required for RPM1-mediated resistance in Arabidopsis [7].

Regulatory relationships of RIN4

• Thus, RIN4 positively regulates RPM1-mediated resistance yet is, formally, a negative regulator of basal defense responses [7].

Other interactions of RIN4

• Therefore, we suggest that RPS2 initiates signaling based upon perception of RIN4 disappearance rather than direct recognition of AvrRpt2 [3].
• Three of four avirulence mutants tested failed to interact with RIN4, an Arabidopsis protein previously shown to be required for RPM1 function [10].
• The activation of RPS2 is coupled to the AvrRpt2-induced disappearance of the A. thaliana RIN4 protein [11].

References