TY - JOUR
T1 - Association of terminal deoxynucleotidyl transferase with Ku
AU - Mahajan, Kiran N.
AU - Gangi-Peterson, Lisa
AU - Sorscher, David H.
AU - Wang, Jingsong
AU - Gathy, Karen N.
AU - Mahajan, Nupam P.
AU - Reeves, Westley H.
AU - Mitchell, Beverly S.
PY - 1999/11/23
Y1 - 1999/11/23
N2 - Terminal deoxynucleotidyl transferase (TdT) catalyzes the addition of nucleotides at the junctions of rearranging Ig and T cell receptor gene segments, thereby generating antigen receptor diversity. Ku is a heterodimeric protein composed of 70- and 86-kDa subunits that binds DNA ends and is required for V(D)J recombination and DNA double-strand break (DSB) repair. We provide evidence for a direct interaction between TdT and Ku proteins. Studies with a baculovirus expression system show that TdT can interact specifically with each of the Ku subunits and with the heterodimer. The interaction between Ku and TdT is also observed in pre-T cells with endogenously expressed proteins. The protein-protein interaction is DNA independent and occurs at physiological salt concentrations. Deletion mutagenesis experiments reveal that the N-terminal region of TdT (131 amino acids) is essential for interaction with the Ku heterodimer. This region, although not important for TdT polymerization activity, contains a BRCA1 C- terminal domain that has been shown to mediate interactions of proteins involved in DNA repair. The induction of DSBs in Cos-7 cells transfected with a human TdT expression construct resulted in the appearance of discrete nuclear foci in which TdT and Ku colocalize. The physical association of TdT with Ku suggests a possible mechanism by which TdT is recruited to the sites of DSBs such as V(D)J recombination intermediates.
AB - Terminal deoxynucleotidyl transferase (TdT) catalyzes the addition of nucleotides at the junctions of rearranging Ig and T cell receptor gene segments, thereby generating antigen receptor diversity. Ku is a heterodimeric protein composed of 70- and 86-kDa subunits that binds DNA ends and is required for V(D)J recombination and DNA double-strand break (DSB) repair. We provide evidence for a direct interaction between TdT and Ku proteins. Studies with a baculovirus expression system show that TdT can interact specifically with each of the Ku subunits and with the heterodimer. The interaction between Ku and TdT is also observed in pre-T cells with endogenously expressed proteins. The protein-protein interaction is DNA independent and occurs at physiological salt concentrations. Deletion mutagenesis experiments reveal that the N-terminal region of TdT (131 amino acids) is essential for interaction with the Ku heterodimer. This region, although not important for TdT polymerization activity, contains a BRCA1 C- terminal domain that has been shown to mediate interactions of proteins involved in DNA repair. The induction of DSBs in Cos-7 cells transfected with a human TdT expression construct resulted in the appearance of discrete nuclear foci in which TdT and Ku colocalize. The physical association of TdT with Ku suggests a possible mechanism by which TdT is recruited to the sites of DSBs such as V(D)J recombination intermediates.
UR - http://www.scopus.com/inward/record.url?scp=0033598831&partnerID=8YFLogxK
U2 - 10.1073/pnas.96.24.13926
DO - 10.1073/pnas.96.24.13926
M3 - Article
C2 - 10570175
AN - SCOPUS:0033598831
SN - 0027-8424
VL - 96
SP - 13926
EP - 13931
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 24
ER -