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Mol. Cell. Biol., 12 1997, 6932-6939, Vol 17, No. 12
W Li, P Swanson and S Desiderio
V(D)J recombination is initiated by RAG-1 and RAG-2, which introduce
double-strand DNA breaks at recombination signal sequences (RSSs) of
antigen receptor gene segments to produce signal ends, terminating in
blunt, double-strand breaks, and coding ends, terminating in DNA hairpins.
While the formation of RAG-RSS complexes has been documented, observations
regarding the individual contributions of RAG-1 and RAG-2 to RSS
recognition are in conflict. Here we describe an assay for formation and
maintenance of functional RAG-RSS complexes in the course of the DNA
cleavage reaction. Under conditions of in vitro cleavage, the RAG proteins
sequester intact substrate DNA in a stable complex which is formed prior to
strand scission. The cleavage reaction subsequently proceeds through
nicking and hairpin formation without dissociation of substrate. Notably,
the presence of both RAG-1 and RAG- 2 is essential for formation of stable,
functional complexes with substrate DNA under conditions of the
sequestration assay. Two classes of substrate mutation are distinguished by
their effects on RAG- mediated DNA cleavage in vitro. A mutation of the
first class, residing within the RSS nonamer and associated with coordinate
impairment of nicking and hairpin formation, greatly reduces the stability
of RAG association with intact substrate DNA. In contrast, a mutation of
the second class, lying within the RSS heptamer and associated with
selective abolition of hairpin formation, has little or no effect on the
half-life of the RAG-substrate complex.
Copyright © 1997, American Society for Microbiology
RAG-1 and RAG-2-dependent assembly of functional complexes with V(D)J recombination substrates in solution
Department of Molecular Biology and Genetics and Howard Hughes Medical Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
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