The homeodomain region of Rag-1 reveals the parallel mechanisms of bacterial and V(D)J recombination.
The V(D)J recombinase subunits Rag-1 and Rag-2 mediate assembly of antigen receptor gene segments. We studied the mechanisms of DNA recognition by Rag-1/Rag-2 using surface plasmon resonance. The critical step for signal recognition is binding of Rag-1 to the nonamer. This is achieved by a region of Rag-1 homologous to the DNA-binding domain of the Hin family of bacterial invertases and to homeodomain proteins. Strikingly, the Hin homeodomain can functionally substitute for the Rag-1 homologous region. Rag-1 also interacts with the heptamer but with low affinity. Rag-2 shows no direct binding to DNA. Once the Rag-1/Rag-2 complex is engaged on the DNA, subsequent cleavage is directed by the heptamer sequence. This order of events remarkably parallels mechanisms that mediate transposition in bacteria and nematodes.
Spanopoulou
E
E
Ruttenberg Cancer Center, Mount Sinai School of Medicine, New York, New York 10029, USA.
Zaitseva
F
F
Wang
F H
FH
Santagata
S
S
Baltimore
D
D
Panayotou
G
G
D000595:Amino Acid Sequence; D001665:Binding Sites; D005075:Biological Evolution; D004254:DNA Nucleotidyltransferases / Q000502:physiology; D004251:DNA Transposable Elements; D004268:DNA-Binding Proteins / Q000737:chemistry; D005801:Genes, Homeobox; D005803:Genes, Immunoglobulin; D018398:Homeodomain Proteins / Q000737:chemistry*; D006801:Humans; D008969:Molecular Sequence Data; D011506:Proteins / Q000737:chemistry*; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D011995:Recombination, Genetic; D013329:Structure-Activity Relationship; D014162:Transfection
D004251:DNA Transposable Elements; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D011506:Proteins; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; C064658:RAG-1 protein; D004254:DNA Nucleotidyltransferases; C059997:Hin recombinase