title: Alkyltransferase-like protein (Atl1) distinguishes alkylated guanines for DNA repair using cation-π interactions.
abstract: Alkyltransferase-like (ATL) proteins in Schizosaccharomyces pombe (Atl1) and Thermus thermophilus (TTHA1564) protect against the adverse effects of DNA alkylation damage by flagging O(6)-alkylguanine lesions for nucleotide excision repair (NER). We show that both ATL proteins bind with high affinity to oligodeoxyribonucleotides containing O(6)-alkylguanines differing in size, polarity, and charge of the alkyl group. However, Atl1 shows a greater ability than TTHA1564 to distinguish between O(6)-alkylguanine and guanine and in an unprecedented mechanism uses Arg69 to probe the electrostatic potential surface of O(6)-alkylguanine, as determined using molecular mechanics calculations. An unexpected consequence of this feature is the recognition of 2,6-diaminopurine and 2-aminopurine, as confirmed in crystal structures of respective Atl1-DNA complexes. O(6)-Alkylguanine and guanine discrimination is diminished for Atl1 R69A and R69F mutants, and S. pombe R69A and R69F mutants are more sensitive toward alkylating agent toxicity, revealing the key role of Arg69 in identifying O(6)-alkylguanines critical for NER recognition.
authors.affiliation: Centre for Chemical Biology, Department of Chemistry, Krebs Institute,  University of Sheffield, Sheffield S3 7HF,  United Kingdom.
authors.forename: Oliver J
authors.initials: OJ
authors.lastname: Wilkinson
authors.forename: Vitaly
authors.initials: V
authors.lastname: Latypov
authors.forename: Julie L
authors.initials: JL
authors.lastname: Tubbs
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Millington
authors.forename: Rihito
authors.initials: R
authors.lastname: Morita
authors.forename: Hannah
authors.initials: H
authors.lastname: Blackburn
authors.forename: Andrew
authors.initials: A
authors.lastname: Marriott
authors.forename: Gail
authors.initials: G
authors.lastname: McGown
authors.forename: Mary
authors.initials: M
authors.lastname: Thorncroft
authors.forename: Amanda J
authors.initials: AJ
authors.lastname: Watson
authors.forename: Bernard A
authors.initials: BA
authors.lastname: Connolly
authors.forename: Jane A
authors.initials: JA
authors.lastname: Grasby
authors.forename: Ryoji
authors.initials: R
authors.lastname: Masui
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Hunter
authors.forename: John A
authors.initials: JA
authors.lastname: Tainer
authors.forename: Geoffrey P
authors.initials: GP
authors.lastname: Margison
authors.forename: David M
authors.initials: DM
authors.lastname: Williams
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000478:Alkylation; D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018360:Crystallography, X-Ray; D004260:DNA Repair / Q000502:physiology*; D006147:Guanine / Q000737:chemistry* / Q000378:metabolism; D020125:Mutation, Missense; D009838:Oligodeoxyribonucleotides / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012568:Schizosaccharomyces / Q000201:enzymology* / Q000235:genetics; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016963:Thermus thermophilus / Q000201:enzymology
chemical_list: D001426:Bacterial Proteins; D009838:Oligodeoxyribonucleotides; D029702:Schizosaccharomyces pombe Proteins; D006147:Guanine; C510506:ATL1 protein, S pombe; D019883:Alkyl and Aryl Transferases