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"The molecular architecture of the mammalian DNA repair enzyme, polynucleotide kinase."
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Bernstein NK, Williams RS, Rakovszky ML, Cui D, Green R, Karimi-Busheri F, Mani RS, Galicia S, Koch CA, Cass CE, Durocher D, Weinfeld M, Glover JN
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Published March 4, 2005
in Mol Cell
volume 17
.
Pubmed ID:
15749016
Abstract:
Mammalian polynucleotide kinase (PNK) is a key component of both the base excision repair (BER) and nonhomologous end-joining (NHEJ) DNA repair pathways. PNK acts as a 5'-kinase/3'-phosphatase to create 5'-phosphate/3'-hydroxyl termini, which are a necessary prerequisite for ligation during repair. PNK is recruited to repair complexes through interactions between its N-terminal FHA domain and phosphorylated components of either pathway. Here, we describe the crystal structure of intact mammalian PNK and a structure of the PNK FHA bound to a cognate phosphopeptide. The kinase domain has a broad substrate binding pocket, which preferentially recognizes double-stranded substrates with recessed 5' termini. In contrast, the phosphatase domain efficiently dephosphorylates single-stranded 3'-phospho termini as well as double-stranded substrates. The FHA domain is linked to the kinase/phosphatase catalytic domain by a flexible tether, and it exhibits a mode of target selection based on electrostatic complementarity between the binding surface and the phosphothreonine peptide.
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Last modification of this entry: Oct. 6, 2010
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