Circularly Permuted Proteins

A circular permutant (CP) is a protein variant characterized by the linking of the two chain ends and cleavage at another site. As a result, CPs have a different position of the N- and C-termini and present a different topology with respect to one another. Both the three-dimensional structure and the function of CPs are generally conserved. The two main genetic mechanisms that have been proposed to originate CPs are fusion/fission and permutation by duplication. Engineering of artificial CPs is increasingly exploited for biotechnological applications and research purposes.