Seminar by Marc Bergdoll (Institute of Plant Molecular Biology)

Title : Structural phylogeny or the construction of gene history from protein structures.

Summary : Like C. Chothia and A. Lesk had shown that, as early as 1986, protein structures and more particularly their folding are better conserved during evolution than their sequences. This property and the impressive accumulation of resolved protein structures now makes it possible to enrich the concept of "structure-function relationship" and to add a "structure-phylogeny relationship" component to it, with the aim of establishing structural phylogenies that are more precise than phylogenies based on sequence alignments. Two examples will be presented dealing with widespread canonical folding. The first one is a family built on the repetition, duplication/fusion and reorganization of a βαβββ module of about sixty amino acids. The second case presented will concern a very common module in the context of viral capsids: the structural domain called jelly-roll. These two examples concern very different superfamilies but have a number of points in common: (i) each is densely populated, (ii) within each of them sequence similarities are almost undetectable, (iii) folding is preserved, and (iv) each derives from a single ancestor following complex pathways, histories.