title: Active-site alkylation destabilizes human O6-alkylguanine DNA alkyltransferase.
abstract: O(6)-alkylguanine-DNA alkyltransferase (AGT) repairs pro-mutagenic O(6)-alkylguanine and O(4)-alkylthymine lesions in DNA. The alkylated form of the protein is not reactivated; instead, it is rapidly ubiquitinated and degraded. Here, we show that alkylation destabilizes the native fold of the protein by 0.5-1.2 kcal/mole and the DNA-binding function by 0.8-1.4 kcal/mole. On this basis, we propose that destabilization of the native conformational ensemble acts as a signal for ubiquitination.
authors.affiliation: Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033, USA.
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Rasimas
authors.forename: Paula A
authors.initials: PA
authors.lastname: Dalessio
authors.forename: Ira J
authors.initials: IJ
authors.lastname: Ropson
authors.forename: Anthony E
authors.initials: AE
authors.lastname: Pegg
authors.forename: Michael G
authors.initials: MG
authors.lastname: Fried
mesh_terms: D000478:Alkylation; D001665:Binding Sites; D002942:Circular Dichroism; D004247:DNA / Q000378:metabolism*; D006801:Humans; D019853:O(6)-Methylguanine-DNA Methyltransferase / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D011489:Protein Denaturation; D017510:Protein Folding; D011994:Recombinant Proteins / Q000378:metabolism; D025801:Ubiquitin / Q000378:metabolism; D014508:Urea / Q000494:pharmacology
chemical_list: D011994:Recombinant Proteins; D025801:Ubiquitin; D014508:Urea; D004247:DNA; D019853:O(6)-Methylguanine-DNA Methyltransferase