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SUMMARY:Artificial evolution of the resistance gene\, Rx\, to enhance acti
 vation sensitivity in a broad recognition background - Jake Harris
DTSTART:20120510T150000Z
DTEND:20120510T153000Z
UID:TALK36388@talks.cam.ac.uk
CONTACT:Suzy Stoodley
DESCRIPTION:Plant Resistance (R) genes provide protection against a divers
 e range of pathogens\, from nematodes to viruses\, with the vast majority 
 encoding proteins from the nucleotide binding leucine-rich repeat (NB-LRR)
  class.  The C-terminal LRR region is thought to provide recognition speci
 ficity\, while the N-terminal NB containing region activates downstream si
 gnalling leading to a defense response.  Previous results from our lab dem
 onstrated that\, in the R gene (Rx)\, the LRR region can be artificially e
 volved to recognise viruses undetected by the wild type Rx protein.  Howev
 er\, some of these broad recognition versions suffer from a reduced activa
 tion response\, with deleterious consequences on plant fitness.  During my
  doctoral research\, I performed random mutagenesis on the N-terminal acti
 vation domains of a broad recognition version of Rx\, and screened approxi
 mately 1500 clones for increased activation characteristics.  I isolated f
 our Rx mutants that show increased defense response without constitutively
  activating the protein\, while retaining the broad recognition phenotype.
   Through homology modelling\, we also revealed that these mutations conce
 ntrate around the ATP/ADP binding site\, which is conserved across all kno
 wn NB-LRRs proteins.  This strategy of targeted evolution\, where recognit
 ion and activation characteristics are sequentially modified\, could poten
 tially be employed to improve disease resistance in crops.
LOCATION:Department of Plant Sciences\, Large Lecture Theatre
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