title: The molecular mechanism of DNA damage recognition by MutS homologs and its consequences for cell death response.
abstract: We determined the molecular mechanism of cell death response by MutS homologs in distinction to the repair event. Key protein-DNA contacts differ in the interaction of MutS homologs with cisplatinated versus mismatched DNA. Mutational analyses of protein-DNA contacts, which were predicted by molecular dynamics (MD) simulations, were performed. Mutations in suggested interaction sites can affect repair and cell death response independently, and to different extents. A glutamate residue is identified as the key contact with cisplatin-DNA. Mutation of the residue increases cisplatin resistance due to increased non-specific DNA binding. In contrast, the conserved phenylalanine that is instrumental and indispensable for mismatch recognition during repair is not required for cisplatin cytotoxicity. These differences in protein-DNA interactions are translated into localized conformational changes that affect nucleotide requirements and inter-subunit interactions. Specifically, the ability for ATP binding/hydrolysis has little consequence for the MMR-dependent damage response. As a consequence, intersubunit contacts are altered that most likely affect the interaction with downstream proteins. We here describe the interaction of MutS homologs with DNA damage, as it differs from the interaction with a mismatch, and its structural translation into all other functional regions of the protein as a mechanism to initiate cell death response and concomitantly inhibit repair.
authors.affiliation: Department of Physics, Wake Forest University, NC 27109, USA.
authors.forename: Freddie R
authors.initials: FR
authors.lastname: Salsbury
authors.forename: Jill E
authors.initials: JE
authors.lastname: Clodfelter
authors.forename: Michael B
authors.initials: MB
authors.lastname: Gentry
authors.forename: Thomas
authors.initials: T
authors.lastname: Hollis
authors.forename: Karin Drotschmann
authors.initials: KD
authors.lastname: Scarpinato
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry; D000970:Antineoplastic Agents / Q000633:toxicity*; D017209:Apoptosis; D001665:Binding Sites; D002945:Cisplatin / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity*; D018736:DNA Adducts / Q000737:chemistry* / Q000378:metabolism; D004249:DNA Damage; D004260:DNA Repair; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018698:Glutamic Acid / Q000737:chemistry; D008958:Models, Molecular; D051719:MutS DNA Mismatch-Binding Protein / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D051718:MutS Homolog 2 Protein / Q000737:chemistry; D009154:Mutation; D010649:Phenylalanine / Q000737:chemistry; D017434:Protein Structure, Tertiary
chemical_list: D000970:Antineoplastic Agents; D018736:DNA Adducts; D029968:Escherichia coli Proteins; C057270:cisplatin-DNA adduct; D018698:Glutamic Acid; D010649:Phenylalanine; D000251:Adenosine Triphosphatases; D051719:MutS DNA Mismatch-Binding Protein; D051718:MutS Homolog 2 Protein; C497175:MutS protein, E coli; D002945:Cisplatin