The R215W mutation in NBS1 impairs gamma-H2AX binding and affects DNA repair: molecular bases for the severe phenotype of 657del5/R215W Nijmegen breakage syndrome patients.
Nijmegen breakage syndrome (NBS) is a genetic disorder characterized by chromosomal instability and hypersensitivity to ionising radiation. Compound heterozygous 657del5/R215W NBS patients display a clinical phenotype more severe than the majority of NBS patients homozygous for the 657del5 mutation. The NBS1 protein, mutated in NBS patients, contains a FHA/BRCT domain necessary for the DNA-double strand break (DSB) damage response. Recently, a second BRCT domain has been identified, however, its role is still unknown. Here, we demonstrate that the R215W mutation in NBS1 impairs histone gamma-H2AX binding after induction of DNA damage, leading to a delay in DNA-DSB rejoining. Molecular modelling reveals that the 215 residue of NBS1 is located between the two BRCT domains, affecting their relative orientation that appears critical for gamma-H2AX binding. Present data represent the first evidence for the role of NBS1 tandem BRCT domains in gamma-H2AX recognition, and could explain the severe phenotype observed in 657del5/R215W NBS patients.
di Masi
Alessandra
A
Department of Biology, University Roma Tre, Viale Guglielmo Marconi 446, I-00146 Roma, Italy.
Viganotti
Mara
M
Polticelli
Fabio
F
Ascenzi
Paolo
P
Tanzarella
Caterina
C
Antoccia
Antonio
A
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics; D001120:Arginine / Q000737:chemistry / Q000235:genetics; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair / Q000235:genetics*; D006657:Histones / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D049932:Nijmegen Breakage Syndrome / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D010641:Phenotype; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D017384:Sequence Deletion; D012720:Severity of Illness Index; D014162:Transfection; D014364:Tryptophan / Q000737:chemistry / Q000235:genetics
D018797:Cell Cycle Proteins; C468783:H2AX protein, human; D006657:Histones; C112156:NBN protein, human; D009687:Nuclear Proteins; D014364:Tryptophan; D001120:Arginine