Amino acid residues in RAG1 responsible for the interaction with RAG2 during the V(D)J recombination process.

The V(D)J recombinase, a complex of RAG1 and RAG2, carries out a gene rearrangement process that is required for the achievement of diverse antigen receptor repertoires during the early developmental stage of lymphocytes. It recognizes a specific site spanning the coding DNA region of antigen receptor genes and produces double-stranded DNA breaks at the board between coding and signal sequences. Two broken DNA ends are joined by a double-stranded break repair system. Both RAG (recombination activation gene) 1 and RAG2 proteins are absolutely required for this process although the catalytic residues of V(D)J recombinase are exclusively located at RAG1 according to recent mutational analyses. In this study we identified some acidic amino acid residues in RAG1 responsible for the interaction with RAG2. Mutation on these residues caused a decrease of cleavage activity in vitro and failure of RAG-RSS DNA synaptic complex formation. This result is complementary to previous reports in which positively charged amino acids in RAG2 play an important role in RAG1 binding.