Background: Nucleoside diphosphate (NDP) kinases provide precursors for DNA and RNA synthesis. In mammals, these enzymes are also involved in cell regulations. Human NDP kinase B, product of the human nm23-H2 gene, is both an enzyme and a transcription factor. It activates transcription of the c-myc oncogene independently of its catalytic function, by binding to its promoter DNA. How do the two functions coexist?

Results: Recombinant human NDP kinase B was co-crystallized with GDP. The X-ray structure was solved at 2.0 A resolution by molecular replacement from the homologous Drosophila Awd protein. Both enzymes are homo-hexamers with a characteristic beta alpha beta beta alpha beta fold. GDP binds near the active site His118. The guanine base is in a surface cleft and interacts with the C terminus of another subunit.

Conclusions: The beta alpha beta beta alpha beta fold, also present in the 'palm' domain of Escherichia coli DNA polymerase I and HIV reverse transcriptase, is both a mononucleotide- and a polynucleotide-binding fold. If NDP kinase B binds DNA in the same way as the polymerases, the enzyme must undergo a conformation change in order to carry out gene activation.

• PMID: 8747457
• DOI full text
• PubMed

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Comparative Study | Journal Article | Research Support, Non-U.S. Gov't

Authors

Moréra S, Lacombe ML, Xu Y, LeBras G, Janin J

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