Towards a R protein crystal structure
Alba de San Eustaquio Campillo
Resistance (R) proteins are a key component of plant innate immunity. R proteins are cytoplasmic immune receptors in plants that recognize specific microbe-associated molecular patterns (MAMPs). This recognition activates the second layer of the immune system in plants, called effector-triggered immunity (ETI).
Most R proteins are multi-domain proteins with a C-terminal leucine-rich repeat (LRR) domain, a central nucleotide-binding (NB)-ARC domain and a variable N-terminal domain. The N-terminal domain can be a coiled-coil (CC) region or a homologue of the Drosophila Toll and mammalian Interleukin-1 Receptors (TIR) structure. R proteins are members of the NB-ARC family of proteins, together with the human Apaf-1 and Caenorhabditis elegans CED-4, apoptosis receptors. The proposed activity of the NB-ARC domain is that of an ATPase. Studies conducted on R proteins have proved them to be ATPases. Nevertheless, a study with a subset of three R proteins showed their main activity was nucleotide phosphatases, not strict ATPases.
In this project, expression, purification, and biochemistry experiments were conducted on Rx, R protein from potato that confers resistance against the potato virus X. Activity assays showed Rx-NBARC constructs to act as nucleotide phosphatases, not strict ATPases, supporting this newly found activity in R proteins
