2bcv
From Proteopedia
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DNA polymerase lambda in complex with Dttp and a DNA duplex containing an unpaired Dtmp
Overview
Insertions and deletions in coding sequences can alter the reading frame of genes and have profound biological consequences. In 1966, Streisinger proposed that these mutations result from strand slippage, which in repetitive sequences generates misaligned intermediates stabilized by correct base pairing that support polymerization. We report here crystal structures of human DNA polymerase lambda, which frequently generates deletion mutations, bound to such intermediates. Each contains an extrahelical template nucleotide upstream of the active site. Surprisingly, the extra nucleotide, even when combined with an adjacent mismatch, does not perturb polymerase active site geometry, which is indistinguishable from that for correctly aligned strands. These structures reveal how pol lambda can polymerize on substrates with minimal homology during repair of double-strand breaks and represent strand-slippage intermediates consistent with Streisinger's classical hypothesis. They are thus relevant to the origin of single-base deletions, a class of mutations that can confer strong biological phenotypes.
About this Structure
2BCV is a Single protein structure of sequence from Homo sapiens with , and as ligands. Full crystallographic information is available from OCA.
Reference
Structural analysis of strand misalignment during DNA synthesis by a human DNA polymerase., Garcia-Diaz M, Bebenek K, Krahn JM, Pedersen LC, Kunkel TA, Cell. 2006 Jan 27;124(2):331-42. PMID:16439207
Page seeded by OCA on Thu Feb 21 16:36:27 2008
Categories: Homo sapiens | Single protein | Bebenek, K. | Garcia-Diaz, M. | Krahn, J M. | Kunkel, T A. | Pedersen, L C. | MG | NA | TTP | Deletion | Extrahelical | Misalignment | Mutagenesis | Mutation | Slippage | Streisinger
