期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2012
卷号：109
期号：46
页码：18755-18760
DOI：10.1073/pnas.1209451109
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Alkyltransferase-like (ATL) proteins in Schizosaccharomyces pombe (Atl1) and Thermus thermophilus (TTHA1564) protect against the adverse effects of DNA alkylation damage by flagging O6-alkylguanine lesions for nucleotide excision repair (NER). We show that both ATL proteins bind with high affinity to oligodeoxyribonucleotides containing O6-alkylguanines differing in size, polarity, and charge of the alkyl group. However, Atl1 shows a greater ability than TTHA1564 to distinguish between O6-alkylguanine and guanine and in an unprecedented mechanism uses Arg69 to probe the electrostatic potential surface of O6-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. O6-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 O6-alkylguanines critical for NER recognition.
