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Terminal deoxynucleotidyltransferase directly interacts with a novel nuclear protein that is homologous to p65
Author(s) -
Yamashita Nobuyuki,
Shimazaki Noriko,
Ibe Shiro,
Kaneko Reo,
Tanabe Akiko,
Toyomoto Tsuguri,
Fujita Kiyoko,
Hasegawa Tomohiko,
Toji Shingo,
Tamai Katsuyuki,
Yamamoto Hiroko,
Koiwai Osamu
Publication year - 2001
Publication title -
genes to cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.912
H-Index - 115
eISSN - 1365-2443
pISSN - 1356-9597
DOI - 10.1046/j.1365-2443.2001.00449.x
Subject(s) - biology , microbiology and biotechnology , protein fragment complementation assay , dna binding protein , terminal deoxynucleotidyl transferase , gene , dna , nuclear protein , in vitro , transcription factor , biochemistry , complementation , mutant , tunel assay , apoptosis
Background Terminal deoxynucleotidyltransferase (TdT) is a DNA polymerase that enhances Ig and TcR gene diversity in the N region in B‐ and T‐cells. TdT is found as a member of a large protein complex in the lysate of the thymocytes. To elucidate the molecular mechanism of the synthesis of the N region, we first attempted to isolate the genes with products that are interacting directly with TdT. Results Using a yeast two‐hybrid system, we isolated a cDNA clone encoding a novel nuclear protein that interacts with TdT. This protein was designated as TdT interacting factor 1 (TdIF1). TdIF1 has a high degree of homology to the transcription factor p65, which belongs to the nuclear receptor superfamily. TdIF1 contains HMG‐I and HMG‐Y DNA binding domains (AT‐hooks) and can bind to single‐ and double‐stranded DNA. TdT and TdIF1 were co‐eluted at position 232 kDa by gel filtration of MOLT4 lysate. TdIF1 can enhance TdT activity fourfold in vitro assay system using oligo(dT) 16 as primers. Conclusions TdIF1 binds directly to TdT, both in vitro and in vivo . TdIF1 and TdT exist as the members of a 232 kDa protein complex. TdIF1 can enhance TdT activity maximum fourfold in vitro assay system, suggesting that it positively regulates the synthesis of the N region during V(D)J recombination in the Ig and TcR genes.