Characterization of the 3' 5' Exonuclease Activity Found in Human Nucleoside Diphosphate Kinase 1 (NDK1) and Several of Its Homologu
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- 作者：Jung-Hoon Yoon ; Purnima Singh ; Dong-Hyun Lee ; Junzhuan Qiu ; Sheng Cai ; Timothy R. O'Connor ; Yuan Chen ; Binghui Shen ; and Gerd P. Pfeifer
- 刊名：Biochemistry
- 出版年：2005
- 出版时间：December 6, 2005
- 年：2005
- 卷：44
- 期：48
- 页码：15774 - 15786
- 全文大小：1119K
- 年卷期：v.44,no.48(December 6, 2005)
- ISSN：1520-4995
文摘
Nucleoside diphoshate kinases (NDKs), an evolutionarily conserved family of proteins,synthesize nucleoside triphosphates from nucleoside diphosphates and ATP. Here, we have characterizedthe kinase activity and DNA processing functions of eight human proteins that contain at least one domainhomologous to Escherichia coli NDK. Not all human proteins with NDK-like domains exhibited NDKactivity when expressed as recombinant proteins in E. coli. Human NDK1 (NM23-H1) has been reportedto have 3' 
5' exonuclease activity. In addition to human NDK1, we also find that human NDK5,NDK7, and NDK8 contain 3' 5' exonuclease activity. Site-directed mutagenesis, competition assaysbetween wild-type and mutant NDK proteins, and NMR studies confirmed that the DNA-binding and3' 5' exonuclease activity of human NDK1 is an intrinsic activity of the protein. Using double-strandedDNA substrates containing modified bases, human NDK1 efficiently excised nucleotides from the single-strand break produced by APE1 or Nth1. When human cells were treated with various DNA-damagingagents, human NDK1 translocated from the cytoplasm to the nucleus. These results suggest that, in additionto maintenance of nucleotide pool balance, the human NDK-like proteins may have previously unrecognizedroles in DNA nucleolytic processing.
5' exonuclease activity. In addition to human NDK1, we also find that human NDK5,NDK7, and NDK8 contain 3' 5' exonuclease activity. Site-directed mutagenesis, competition assaysbetween wild-type and mutant NDK proteins, and NMR studies confirmed that the DNA-binding and3' 5' exonuclease activity of human NDK1 is an intrinsic activity of the protein. Using double-strandedDNA substrates containing modified bases, human NDK1 efficiently excised nucleotides from the single-strand break produced by APE1 or Nth1. When human cells were treated with various DNA-damagingagents, human NDK1 translocated from the cytoplasm to the nucleus. These results suggest that, in additionto maintenance of nucleotide pool balance, the human NDK-like proteins may have previously unrecognizedroles in DNA nucleolytic processing.