The Arabidopsis thaliana RPM1 disease resistance gene product is a peripheral plasma membrane protein that is degraded coincident with the hypersensitive response

Disease resistance in plants is often controlled by a gene-for-gene mechani sm in which avirulence (avr) gene products encoded by pathogens are specifi cally recognized, either directly or indirectly, by plant disease resistanc e (R) gene products, Members of the NBS-LRR class of R genes encode protein s containing a putative nucleotide binding site (NBS) and carboxyl-terminal leucine-rich repeats (LRRs), Generally, NBS-LRR proteins do not contain pr edicted transmembrane segments or signal peptides, suggesting they are solu ble cytoplasmic proteins. RPM1 is an NBS-LRR protein from Arabidopsis thali ana that confers resistance to Pseudomonas syringae expressing either avrRp m1 or avrB, RPM1 protein was localized by using an epitope tag. In contrast to previous suggestions, RPM1 is a peripheral membrane protein that likely resides on the cytoplasmic face of the plasma membrane. Furthermore, RPM1 is degraded coincident with the onset of the hypersensitive response, sugge sting a negative feedback loop controlling the extent of cell death and ove rall resistance response at the site of infection.