title: SOS factors involved in translesion synthesis.
abstract: Mutations are permanent DNA sequence changes that can be induced when replication occurs on a damaged DNA template. In Escherichia coli, the process of translesion synthesis past a lesion that hinders replication requires the induction of SOS-controlled gene products, among which are those of the umuDC operon. To study translesion synthesis in vivo, we have constructed single-stranded vectors containing single 2-acetylaminofluorene adducts located within -1 and -2 frameshift mutation hot spots formed by short repetitive sequences. These adducts strongly hinder DNA replication as only 2-5% of the molecules give rise to progeny under non-SOS-induced conditions. Induction of the SOS response lead to a 10-fold increase in survival. Adducts present within repetitive sequences trigger the formation of misaligned primer/template replication intermediates which, upon elongation, will result in the fixation of frameshift errors (mutagenic translesion synthesis). Surprisingly we find that elongation from the nonslipped intermediate depends upon functional umuDC+ gene products, whereas elongation from the slipped intermediate is umuDC+ independent but requires another, as yet biochemically uncharacterized, SOS function. These data are discussed in terms of the different steps involved during translesion synthesis through a replication-blocking lesion.
authors.affiliation: Unité Propre de Recherche 9003 du Centre National de la Recherche Scientifique, Cancérogenèse et Mutagenèse Moléculaire et Structurale, Ecole Supérieure de Biotechnologie de Strasbourg, Blvd S. Brant, 67400 Strasbourg, France.
authors.forename: R L
authors.initials: RL
authors.lastname: Napolitano
authors.forename: I B
authors.initials: IB
authors.lastname: Lambert
authors.forename: R P
authors.initials: RP
authors.lastname: Fuchs
mesh_terms: D015073:2-Acetylaminofluorene / Q000494:pharmacology; D004249:DNA Damage; D004261:DNA Replication; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D016368:Frameshift Mutation; D008957:Models, Genetic; D016296:Mutagenesis; D009153:Mutagens / Q000494:pharmacology; D015345:Oligonucleotide Probes; D009876:Operon; D013014:SOS Response, Genetics; D013698:Templates, Genetic
chemical_list: D009153:Mutagens; D015345:Oligonucleotide Probes; D015073:2-Acetylaminofluorene; D004259:DNA-Directed DNA Polymerase