A PHD finger motif in the C terminus of RAG2 modulates recombination activity.
The RAG1 and RAG2 proteins catalyze V(D)J recombination and are essential for generation of the diverse repertoire of antigen receptor genes and effective immune responses. RAG2 is composed of a "core" domain that is required for the recombination reaction and a C-terminal nonessential or "non-core" region. Recent evidence has emerged arguing that the non-core region plays a critical regulatory role in the recombination reaction, and mutations in this region have been identified in patients with immunodeficiencies. Here we present the first structural data for the RAG2 protein, using NMR spectroscopy to demonstrate that the C terminus of RAG2 contains a noncanonical PHD finger. All of the non-core mutations of RAG2 that are implicated in the development of immunodeficiencies are located within the PHD finger, at either zinc-coordinating residues or residues adjacent to an alpha-helix on the surface of the domain that participates in binding to the signaling molecules, phosphoinositides. Functional analysis of disease and phosphoinositide-binding mutations reveals novel intramolecular interactions within the non-core region and suggests that the PHD finger adopts two distinct states. We propose a model in which the equilibrium between these states modulates recombination activity. Together, these data identify the PHD finger as a novel and functionally important domain of RAG2.
Elkin
Sheryl K
SK
Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
Ivanov
Dmitri
D
Ewalt
Mark
M
Ferguson
Colin G
CG
Hyberts
Sven G
SG
Sun
Zhen-Yu J
ZY
Prestwich
Glenn D
GD
Yuan
Junying
J
Wagner
Gerhard
G
Oettinger
Marjorie A
MA
Gozani
Or P
OP
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D016384:Consensus Sequence; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D007700:Kinetics; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011995:Recombination, Genetic; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D045567:VDJ Recombinases / Q000378:metabolism*; D016335:Zinc Fingers
D004268:DNA-Binding Proteins; C499308:Rag2 protein, mouse; C064655:V(D)J recombination activating protein 2; D045567:VDJ Recombinases