title: RecA acts in trans to allow replication of damaged DNA by DNA polymerase V.
abstract: The DNA polymerase V (pol V) and RecA proteins are essential components of a mutagenic translesion synthesis pathway in Escherichia coli designed to cope with DNA damage. Previously, it has been assumed that RecA binds to the DNA template strand being copied. Here we show, however, that pol-V-catalysed translesion synthesis, in the presence or absence of the beta-processivity-clamp, occurs only when RecA nucleoprotein filaments assemble or RecA protomers bind on separate single-stranded (ss)DNA molecules in trans. A 3'-proximal RecA filament end on trans DNA is essential for stimulation; however, synthesis is strengthened by further pol V-RecA interactions occurring elsewhere along a trans nucleoprotein filament. We suggest that trans-stimulation of pol V by RecA bound to ssDNA reflects a distinctive regulatory mechanism of mutation that resolves the paradox of RecA filaments assembled in cis on a damaged template strand obstructing translesion DNA synthesis despite the absolute requirement of RecA for SOS mutagenesis.
authors.affiliation: Department of Biological Sciences and Chemistry, University of Southern California, University Park, Los Angeles, California 90089-2910, USA.
authors.forename: Katharina
authors.initials: K
authors.lastname: Schlacher
authors.forename: Michael M
authors.initials: MM
authors.lastname: Cox
authors.forename: Roger
authors.initials: R
authors.lastname: Woodgate
authors.forename: Myron F
authors.initials: MF
authors.lastname: Goodman
mesh_terms: D002384:Catalysis; D004249:DNA Damage; D004261:DNA Replication; D004277:DNA, Single-Stranded / Q000235:genetics / Q000378:metabolism; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D029968:Escherichia coli Proteins; D007700:Kinetics; D009154:Mutation / Q000235:genetics; D011938:Rec A Recombinases / Q000235:genetics / Q000378:metabolism*; D013014:SOS Response, Genetics; D013698:Templates, Genetic; D015533:Transcriptional Activation
chemical_list: D004277:DNA, Single-Stranded; D029968:Escherichia coli Proteins; D011938:Rec A Recombinases; C120926:DNA polymerase V, E coli; D004259:DNA-Directed DNA Polymerase