Association of terminal deoxynucleotidyl transferase with Ku

Kiran N. Mahajan, Lisa Gangi-Peterson, David H. Sorscher, Jingsong Wang, Karen N. Gathy, Nupam P. Mahajan, Westley H. Reeves, Beverly S. Mitchell

Research output: Contribution to journalArticlepeer-review

75 Scopus citations

Abstract

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.

Original languageEnglish
Pages (from-to)13926-13931
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume96
Issue number24
DOIs
StatePublished - Nov 23 1999

Fingerprint

Dive into the research topics of 'Association of terminal deoxynucleotidyl transferase with Ku'. Together they form a unique fingerprint.

Cite this