Recombination signal sequence (RSS)

The Recombination Signal Sequence (RSS) is a conserved DNA motif located adjacent to the Variable (V), Diversity (D), and Joining (J) gene segments within the immunoglobulin and T-cell receptor loci (Schatz & Swanson, 2011). Each RSS consists of a conserved heptamer and nonamer separated by a non-conserved spacer of either 12 or 23 base pairs, which dictates the 12/23 rule of recombination (Gellert, 2002). This sequence is specifically recognized and bound by the RAG1/RAG2 endonuclease complex, which initiates the DNA double-strand breaks necessary for V(D)J recombination (Teng & Papavasiliou, 2007). This process is essential for generating the vast diversity of the adaptive immune system's antigen receptors. While the RSS is not a traditional target for pharmacological agents, its proper function is critical for immune health; mutations in these sequences can lead to Severe Combined Immunodeficiency (SCID) (Notarangelo, 2010). Conversely, mistargeted RAG activity at RSS-like sequences (cryptic RSS) can lead to chromosomal translocations, a hallmark of many lymphoid leukemias and lymphomas (Helmink & Sleckman, 2012). Understanding the RSS-RAG interaction is vital for developing strategies to mitigate genomic instability and for advancing gene therapy approaches in primary immunodeficiencies.

Other names

V(D)J recombination signal sequence12-RSS23-RSSHeptamer-spacer-nonamer motif

The RSS serves as the specific recognition and binding site for the RAG1/RAG2 endonuclease complex; RAG1 binds the nonamer, and the complex introduces double-strand breaks at the heptamer-coding segment junction to initiate V(D)J recombination (Schatz & Swanson, 2011).