Definition of minimal domains of interaction within the recombination-activating genes 1 and 2 recombinase complex

During V(D)J recombination, recognition and cleavage of the recombination s ignal sequences (KSSs) requires the coordinated action of the recombination -activating genes 1 and 2 (RAG1/RAG2) recombinase complex, In this report, we use deletion mapping and site-directed mutagenesis to determine the mini mal domains critical for interaction between RAG1 and RAG2. We define the a ctive core of RAG2 required for RSS cleavage as aa 1-371 and demonstrate th at the C-terminal 57 aa of this core provide a dominant surface for RAG1 in teraction. This region corresponds to the last of sis predicted kelch repea t motifs that have been proposed by sequence analysis to fold RAG2 into a s ix-bladed beta-propeller structure, Residue W317 within this sixth repeat i s shown to be critical for mediating contact with RAG1 and concurrently for stabilizing binding and directing cleavage of the RSS, We also show that z inc finger B (aa 727-750) of RAG1 provides a dominant interaction domain fo r recruiting RAG2, in all, the data support a model of RAG2 as a multimodul ar protein that utilizes one of its sis faces for establishing productive c ontacts with RAG1.