Evolution domain swapping

The following diagram, adapted from that first presented by Bennett et alC, describes a postulated pathway for evolution of a protein dimer from single-domain proteins. The scheme begins with the fusion of two singledomain polypeptides and proceeds through the evolution of interdomain contacts, and in the case of enzymes, development of an active site. These same interdomain contacts can also stabilize formation of a domain-swapped dimer which then undergoes further evolution into a present-day dimer. 

M. Ostermeier and S.). Benkovic, Evolution of protein function by domain swapping, Adv. Protein Chem. 2000, 55, 29-77. 

The following sections explore nature s use of domain swapping to evolve new function. These include the formation of multifunctional proteins, tandem duplication, domain recruitment, and cicular permutation (Fig. 1). The evolution of several enzymes in the purine (Fig. 2) and pyrimidine (Fig. 3) de novo biosynthetic pathways, as well as other enzymes, are discussed as illustrative examples. 

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