Identification of a minimal functional linker in human topoisomerase I by domain swapping with Cre recombinase.

Cellular forms of type IB topoisomerases distinguish themselves from their viral counterparts and the tyrosine recombinases to which they are closely related by having rather extensive N-terminal and linker domains. The functions and necessity of these domains are not yet fully unraveled. In this study we replace 86 amino acids including the linker domain of the cellular type IB topoisomerase, human topoisomerase I, with four, six, or eight amino acids from the corresponding short loop region in Cre recombinase.