The subtle benefits of being promiscuous: adaptive evolution potentiated by enzyme promiscuity.

In this commentary we discuss recent progress in our understanding of adaptive protein evolution. We begin with a general introduction to proteins and their evolution, quickly focusing on the question of how natural selection produces proteins with novel functions. We then summarize the theory of latent protein adaptation advanced by the joint articles by Amitai et al. (2007), HFSP J. 1, 67-78 and Wroe et al. (2007) HFSP J. 1, 79-87, published in the first issue edition of the HFSP Journal. This theory provides a biophysical framework linking the effects of individual mutations on promiscuous protein function, neutral genetic drift, and gene duplication to the process of adaptive protein evolution.