Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
2833236 | Molecular Immunology | 2006 | 12 Pages |
Abstract
In mice, κ light chains dominate over λ in the immunoglobulin repertoire by as much as 20-fold. Although a major contributor to this difference is the recombination signal sequences (RSS), the mechanism by which RSS cause differential representation has not been determined. To elucidate the mechanism, we tested κ and λ RSS flanked by their natural 5Ⲡand 3Ⲡflanks in three systems that monitor V(D)J recombination. Using extra-chromosomal recombination substrates, we established that a κ RSS and its flanks support six- to nine-fold higher levels of recombination than a λ counterpart. In vitro cleavage assays with these same sequences demonstrated that single cleavage at individual κ or λ RSS (plus flanks) occurs with comparable frequencies, but that a pair of κ RSS (plus flanks) support significantly higher levels of double cleavage than a pair of λ RSS (plus flanks). Using EMSA with double stranded oligonucleotides containing the same κ or λ RSS and their respective flanks, we examined RAG/DNA complex formation. We report that, surprisingly, RAG-1/2 form only modestly higher levels of complexes on individual 12 and 23 κ RSS (plus natural flanks) as compared to their λ counterparts. We conclude that the overuse of κ compared to λ segments cannot be accounted for by differences in RAG-1/2 binding nor by cleavage at individual RSS but rather could be accounted for by enhanced pair-wise cleavage of κ RSS by RAG-1/2. Based on the data presented, we suggest that the biased usage of light chain segments is imposed at the level of synaptic RSS pairs.
Keywords
Related Topics
Life Sciences
Biochemistry, Genetics and Molecular Biology
Molecular Biology
Authors
Mani Larijani, Shuang Chen, Lesley A. Cunningham, Joseph M. Volpe, Lindsay Grey Cowell, Susanna M. Lewis, Gillian E. Wu,