V(D)J RECOMBINATION SIGNAL RECOGNITION - DISTINCT, OVERLAPPING DNA-PROTEIN CONTACTS IN COMPLEXES CONTAINING RAG1 WITH AND WITHOUT RAG2

Protein interactions with V(D)J recombination signal sequences (RSSs) were mapped in complexes containing RAG1 with (M1/2) or without (M1) R AGS. In both complexes, RAG interactions with the DNA backbone are bia sed toward one side of the helix; nonamer contacts resemble those of H in with hixL. In the M1 complex, DNA contacts are centered on the nona mer. In the M1/2 complex, protein-RSS interactions extend through the spacer and into the nonamer-proximal portion of the heptamer. Chemical modifications near the heptamer-coding junction are overrepresented i n the M1/2 complex, providing evidence for perturbation of DNA structu re in this region. Thus, while RAG1 alone can bind the nonamer, RAGS i s required for heptamer occupancy.