Interactions of Human O6-Alkylguanine-DNA Alkyltransferase (AGT) with Short Double-Stranded DNAs
- 5 December 2008
- journal article
- research article
- Published by American Chemical Society (ACS) in Biochemistry
- Vol. 47 (52), 13754-13763
- https://doi.org/10.1021/bi801666c
Abstract
O6-alkylguanine-DNA alkyltransferase (AGT) is a ubiquitous enzyme with an amino acid sequence that is conserved in Eubacteria, Archaea, and Eukarya. It repairs O6-alkylguanine and O4-alkylthymine adducts in single-stranded and duplex DNAs. In performing these functions, AGT must partition between adduct-containing sites and the large excess of adduct-free DNA distributed throughout the genome. Here, we characterize the binding of human AGT to linear double-stranded, adduct-free DNAs ranging in length from 11 bp to 2686 bp. Moderately cooperative binding (22.6 ± 3.7 ≤ ω ≤ 145.0 ± 37.0) results in an all-or-nothing association pattern on short templates. The apparent binding site size Sapp (mean = 4.39 ± 0.02 bp) oscillates with increasing template length. Oscillations in cooperativity factor ω have the same frequency but are of opposite phase to Sapp, with the result that the most stable protein−protein and protein−DNA interactions occur at the highest packing densities. The oscillation period (4.05 ± 0.02 bp/protein) is nearly identical to the occluded binding site size obtained at the highest measured binding density (4 bp/protein) and is significantly smaller than the contour length (∼8 bp) occupied in crystalline complexes. A model in which protein molecules overlap along the DNA contour is proposed to account for these features. High AGT densities resulting from cooperative binding may allow efficient search for lesions in the context of chromatin remodeling and DNA replication.Keywords
This publication has 44 references indexed in Scilit:
- O6-Methylguanine-DNA methyltransferase inactivation and chemotherapyBritish Medical Bulletin, 2008
- Interactions of Human O6-Alkylguanine-DNA Alkyltransferase (AGT) with Short Single-stranded DNAsOnline Journal of Public Health Informatics, 2007
- The Structure of the Human AGT Protein Bound to DNA and its Implications for Damage DetectionJournal of Molecular Biology, 2005
- Alteration of arginine-128 to alanine abolishes the ability of human O6-alkylguanine-DNA alkyltransferase to repair methylated DNA but has no effect on its reaction with O6-benzylguanineBiochemistry, 1995
- Factors Influencing the Repair of the Mutagenic Lesion O6-methylguanine in DNA by Human O6-methylguanine-DNA MethyltransferaseJournal of Molecular Biology, 1993
- Chromatin reconstituted from tandemly repeated cloned DNA fragments and core histones: A model system for study of higher order structureCell, 1985
- The dimensions of DNA in solutionJournal of Molecular Biology, 1981
- Theoretical aspects of DNA-protein interactions: Co-operative and non-co-operative binding of large ligands to a one-dimensional homogeneous latticeJournal of Molecular Biology, 1974
- Cleavage of Structural Proteins during the Assembly of the Head of Bacteriophage T4Nature, 1970
- Absorption and Optical Rotatory Dispersion of Seven Trinucleoside DiphosphatesJournal of Molecular Biology, 1965