The RAG1 N-terminal region regulates the efficiency and pathways of synapsis for V(D)J recombination

The RAG1 N-terminal region (NTR; aa 1-383) has been implicated in regulatory functions whose influence on V(D)J recombination and lymphocyte development in vivo are poorly understood. We generated mice in which RAG1 lacks ubiquitin ligase activity (P326G), the major site of autoubiquitination (K233R), or its first 215 residues (d215).

While few abnormalities were detected in R1.K233R mice, R1.P326G mice exhibit multiple features indicative of reduced recombination efficiency including an increased Igk+:Igl+ B cell ratio and decreased recombination of Igh, Igk, Igl, and Tcrb loci. Previous studies indicate that synapsis of recombining partners during Igh recombination occurs through two pathways: long-range scanning and short-range collision. We find that R1d215 mice exhibit reduced short-range Igh and Tcrb D-to-J recombination.