Involved in DNA damage recognition. Binds DNA containing O(6)-methylguanine and larger O(6)-alkylguanine adducts (PubMed:18483064, PubMed:23112169). Binds to the damaged base and flips the base out of the DNA duplex into an extrahelical conformation, which allows processing by repair proteins (PubMed:18483064). Also affects the regulation of gene expression in response to alkylation (PubMed:21531768). Interacts with several proteins, including UvrA, UvrD and the three subunits of the RNA polymerase. Disruption increases the spontaneous mutation rate. Belongs to the MGMT family. ATL subfamily.