Abstract
TdT interacting factor 1 (TdIF1) was identified as a protein that binds to terminal deoxynucleotidyltransferase (TdT) to negatively regulate TdT activity. TdT is a template-independent DNA polymerase that catalyzes the incorporation of deoxynucleotides to the 3'-hydroxyl end of DNA templates to increase the junctional diversity of immunoglobulin or T-cell receptor (TcR) genes. Here, using bioinformatics analysis, we identified the TdT binding, DNA binding and dimerization regions, and nuclear localization signal (NLS) in TdIF1. TdIF1 bound to double-stranded DNA (dsDNA) through three DNA binding regions: residues 1-75, the AT-hook-like motif (ALM) and the predicted helix-turn-helix (HTH) motif. ALM in TdIF1 preferentially bound to AT-rich DNA regions. NLS was of the bipartite type and overlapped ALM. TdIF1 bound to the Pol beta-like region in TdT and blocked TdT access to DNA ends. In the presence of dsDNA, however, TdIF1 bound to dsDNA to release TdT from the TdIF1/TdT complex and to exhibit TdT activity, implying that active TdT released microenvironmentally concentrates around AT-rich DNA to synthesize DNA.
Original language | English |
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Pages (from-to) | 941-959 |
Number of pages | 19 |
Journal | Genes to Cells |
Volume | 12 |
Issue number | 8 |
Early online date | 27 Jul 2007 |
DOIs | |
Publication status | Published - Aug 2007 |
Keywords
- AT Rich Sequence
- Amino Acid Motifs
- Amino Acid Sequence
- Carrier Proteins
- Cell Nucleus
- DNA Nucleotidylexotransferase
- DNA, Single-Stranded
- DNA-Directed DNA Polymerase
- Dimerization
- HeLa Cells
- Humans
- Molecular Sequence Data
- Nuclear Localization Signals
- Nuclear Proteins
- Protein Binding
- Protein Structure, Tertiary
- Sequence Alignment
- Sequence Homology, Amino Acid