Sergei Maslov, Kim Sneppen, and Kasper Astrup Eriksen
Upstream Plasticity and Downstream Robustness in Evolution of Molecular Networks
submitted to BMC Evolutionary Biology

Gene duplication followed by functional divergence of associated proteins is a major force shaping molecular networks in living organisms. Recent availability of system-wide data for yeast S. Cerevisiae allow us to access the effects of gene duplication on robustness and plasticity of molecular networks.

We demonstrate that the upstream transcriptional regulation of duplicated genes diverges fast, losing on average 4% of their common transcription factors for every 1% divergence of their amino acid sequences. In contrast, the set of physical interaction partners of their protein products changes much slower. The relative stability of downstream functions of duplicated genes, is further corroborated by their ability to substitute for each other in gene knockout experiments.

Apparently the upstream regulation of genes evolves much more rapidly than the downstream functions of the associated proteins. This is in accordance with a view where it is regulatory changes that mainly drives evolution. Any evolutionary model has eventually to account for this disparity and we have here quantified its size on a genome wide scale. In this context a very important open question is to what extent our results for duplicated genes within yeast (paralogs) carries over to homologeous proteins in different species (orthologs).

LU TP 03-46