Control of protein conformation by the Protein L-isoaspartyl methyltransferase (PIMT) in Arabidopsis and seed
responses to environmental stress: repair or signaling role?

We recently established that the protein repair L-isoaspartyl methyltransferase (PIMT) is required for seed survival in Arabidopsis both during dry storage and germination in stressful conditions (Ogé et al, 2008 Plant Cell 20: 3022-3037). We showed that this enzyme contributes to seed survival by combating protein misfolding originating from detrimental Lisoaspartyl (isoAsp) accumulation in seed proteins. PIMT mutant phenotypes and subcellular localizations strongly suggest that this enzyme controls the conformation and activity of specific proteins controlling stress response. In this PhD project we are willing to establish (1) the isoaspartome of seeds submitted to abiotic stresses and tolerance inducing conditions, (2) the exact nature of the proteins specifically targeted by PIMT post-translational modification, and (3) the control PIMT gene expression. We anticipate that the results will open up new avenues to unravel the specific mechanisms accounting for the spectacular resistance of seeds to adverse environments. Since isoAsp formation is a spontaneous damage that afflict protein conformation under oxidative stress, the present study aims at unveiling the mechanisms by which PIMT repair pathway could modulates the activity of specific proteins involved in stress response, which is of major importance in plants and in general all living organisms.

PhD subject IJPB 2011 from research group Germination physiology