title: Role of RAG1 autoubiquitination in V(D)J recombination.
abstract: The variable domains of Ig and T-cell receptor genes in vertebrates are assembled from gene fragments by the V(D)J recombination process. The RAG1-RAG2 recombinase (RAG1/2) initiates this recombination by cutting DNA at the borders of recombination signal sequences (RSS) and their neighboring gene segments. The RAG1 protein is also known to contain a ubiquitin E3 ligase activity, located in an N-terminal region that is not strictly required for the basic recombination reaction but helps to regulate recombination. The isolated E3 ligase domain was earlier shown to ubiquitinate one site in a neighboring RAG1 sequence. Here we show that autoubiquitination of full-length RAG1 at this specific residue (K233) results in a large increase of DNA cleavage by RAG1/2. A mutational block of the ubiquitination site abolishes this effect and inhibits recombination of a test substrate in mouse cells. Thus, ubiquitination of RAG1, which can be promoted by RAG1's own ubiquitin ligase activity, plays a significant role in governing the level of V(D)J recombination activity.
authors.affiliation: Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892.
authors.forename: Samarendra K
authors.initials: SK
authors.lastname: Singh
authors.affiliation: Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892 gellert@helix.nih.gov.
authors.forename: Martin
authors.initials: M
authors.lastname: Gellert
mesh_terms: D000818:Animals; D053837:DNA Cleavage; D018398:Homeodomain Proteins / Q000378:metabolism*; D051379:Mice; D054875:Ubiquitination; D060152:V(D)J Recombination
chemical_list: D018398:Homeodomain Proteins; C064658:RAG-1 protein
keywords: diversification; immunoglobulin; ubiquitin