Date

May 10, 2013

Time

2:00 pm

Location

RW432

Cristian Landry, Laval University

Host: Belinda Chang

ABSTRACT

My laboratory is interested in the evolution of the inner life of cells. Using integrative approaches, we investigate several aspects of the evolution of protein interaction networks (PINs). First, we study the evolution of kinase-substrate networks in order to investigate whether PINs contain non-functional interactions. Using phosphoproteomics data from human and yeast, we found that kinase-substrate networks may contain a significant fraction of non-functional phosphorylation sites. Neutral evolutionary forces therefore need to be considered in the study of the evolution and function of PINs. Second, we study the role of transcriptional divergence between paralogous genes in the rewiring of PINs after gene duplication. By analysing existing data on the yeast PINs and transcriptional networks, we show that the more coordinated the transcriptional programs of paralogous genes are, the more similar their PINs are. Using genome engineering, we swapped the coding sequences between paralogous genes and investigated their PINs. Our results suggest that PINs could be rewired after gene duplication by changes in the transcriptional program alone, without the need for coding sequence changes. Finally, we investigate the assembly of protein complexes in hybrids between species. Interacting proteins are expected to co-evolve within species to avoid spurious interactions and maintain functional ones. These relationships are predicted to breakdown in hybrids between species. Our experimental results so far show that protein complexes may be robust to inter-species hybridization and that the breakdown of co-evolved complexes may be less likely than generally assumed.