title: Single-stranded DNA binding proteins unwind the newly synthesized double-stranded DNA of model miniforks.
abstract: Single-stranded DNA binding (SSB) proteins are essential proteins of DNA metabolism. We characterized the binding of the bacteriophage T4 SSB, Escherichia coli SSB, human replication protein A (hRPA), and human hSSB1 proteins onto model miniforks and double-stranded-single-stranded (ds-ss) junctions exposing 3' or 5' ssDNA overhangs. T4 SSB proteins, E. coli SSB proteins, and hRPA have a different binding preference for the ss tail exposed on model miniforks and ds-ss junctions. The T4 SSB protein preferentially binds substrates with 5' ss tails, whereas the E. coli SSB protein and hRPA show a preference for substrates with 3' ss overhangs. When interacting with ds-ss junctions or miniforks, the T4 SSB protein, E. coli SSB protein, and hRPA can destabilize not only the ds part of a ds-ss junction but also the daughter ds arm of a minifork. The T4 SSB protein displays these unwinding activities in a polar manner. Taken together, our results position the SSB protein as a potential key player in the reversal of a stalled replication fork and in gap repair-mediated repetitive sequence expansion.
authors.affiliation: Institut Jacques Monod, UMR7592, "Pathologies de la réplication de l'ADN", CNRS, Paris, France. delagoutte.emmanuelle@ijm.univ-paris-diderot.fr
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Delagoutte
authors.forename: Amélie
authors.initials: A
authors.lastname: Heneman-Masurel
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Baldacci
mesh_terms: D001665:Binding Sites; D004247:DNA / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D024101:Mitochondrial Proteins; D008954:Models, Biological; D011485:Protein Binding; D051716:Replication Protein A / Q000737:chemistry / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D024101:Mitochondrial Proteins; D051716:Replication Protein A; C504091:NABP2 protein, human; D004247:DNA