Sandbox GGC9

RAG1 is the catalytic component of the RAG Complex. Together with RAG2, the RAG Complex functions to create antibodies for virtually any antigen.

Function

RAG1 and RAG2 form the RAG Complex (RAG Recombinases), which is responsible for regulating the DNA cleavage phase during recombination. V(D)J recombination functions to produce a plethora of immune molecules in developing B and T-lymphocytes. The V stands for variable, D, diversity and J joining of the gene segments. RAG1 functions as the catalytic portion while RAG2, although not catalytic, is required for RAG1 to function.[1] RAG1 controls the ability of the DNA to bind to the RSS or recombination signal sequences. This is achieved by the ability of the RAG1 complex to create a double-stranded break between the (RSS) and the adjacent coding sequence. This process is executed in the following way: introduction of a nick, creating a 3'-hydroxyl group which attacks the phosphodiester bond on the opposite strand.[1] This is a direct transesterification reaction which results in four DNA ends. Histones also assist in the nicking and hairpinning of the strands. The result is the recombination of variable genes joining.[1] Additionally to the role played in V(D)J, RAG also assists in pre-B cell allelic exclusion. This means that there is a recombination of the second allele. RAG1 also possess ubiquitin properties. Newer Studies suggest that the RAG1/2 recombinase complex acts as a domesticated transposase.[2]

Disease

Mutations of the RAG recombinases are often occurring in patients being displaying immunodeficiency and Omenn syndrome. [3] Omenn's syndrome is a severe combined immunodeficiency. [4] Some characteristics include redness of skin, peeling skin, hair loss, chronic diarrhea, enlarged lymph nodes, swelling of liver and spleen, and increased levels of of serum IgE. [4]

(Hsu et al 2011)

Relevance

Early intervention of people with Omenn's syndrome is important, because if left untreated it will be fatal. [4] Treatment of Omenn's syndrome includes bone marrow or cord blood stem cell transplantation. [4]

Structural highlights

The subunit structure is defined as a homodimer.

The zinc site plays an important role in DNA cleavage; without the zinc site the DNA would not be able to be cleaved and would not form the essential hairpin structure.[5]

Recent studies identified aspartic acid residues at positions 600 and 708 function to initiate catalysis.[7]