title: [Chemically methylated DNA repair in Escherichia coli--the role of alkB protein].
abstract: Methylating agents belong to mutagens occurring most frequently in our environment. They methylate mainly the nitrogen bases in DNA and RNA, affecting their functions. In E. coli the alkylated bases are repaired by proteins and enzymes either permanently present in the cells (Ogt, Ada) or produced transiently (Ada, AlkB, AlkA, Aid), after induction of the Ada defence system. Alkylating agents induce also the SOS system, which enhances the synthesis of about 40 proteins, including those participating in recombination, replication and mutagenesis of DNA. All DNA interactions, modifications and repairs constitute an amazing and highly efficiently functioning cellular system. Among the repair proteins there are some which affect the alkylated bases in a non-conventional way, very rarely occurring in nature. Especially amazing is the mechanism of action of dioxogenase AlkB, which combines the repair of methyl-, ethyl- and etheno-base derivatives with oxidation and dissociation of the modified groups, leading to direct recovery of natural bases. This review attempts to elucidate the role of the individual proteins involved in the repair processes.
authors.affiliation: Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 5A Pawińskiego St., 02-106 Warszawa, Poland. celina@ibb.waw.pl
authors.forename: Celina
authors.initials: C
authors.lastname: Janion
mesh_terms: D000477:Alkylating Agents / Q000737:chemistry / Q000633:toxicity*; D004249:DNA Damage; D045647:DNA Glycosylases / Q000378:metabolism; D019175:DNA Methylation / Q000187:drug effects*; D004260:DNA Repair; D045643:DNA Repair Enzymes / Q000378:metabolism; D004269:DNA, Bacterial / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D008769:Methylnitronitrosoguanidine / Q000737:chemistry; D008770:Methylnitrosourea / Q000737:chemistry; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D009153:Mutagens / Q000633:toxicity*; D019853:O(6)-Methylguanine-DNA Methyltransferase / Q000378:metabolism; D013014:SOS Response, Genetics; D014157:Transcription Factors / Q000378:metabolism
chemical_list: C090096:AidB protein, E coli; D000477:Alkylating Agents; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D009153:Mutagens; D014157:Transcription Factors; D008769:Methylnitronitrosoguanidine; D008770:Methylnitrosourea; D006899:Mixed Function Oxygenases; C466427:AlkB protein, E coli; C045675:Ada protein, E coli; D019853:O(6)-Methylguanine-DNA Methyltransferase; D045647:DNA Glycosylases; C076131:DNA-3-methyladenine glycosidase II; D045643:DNA Repair Enzymes