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The DNA binding and ATPase activities of RecF protein are modulated by RecR protein. Stoichiometric amounts of RecF protein bind to double-stranded (ds) DNA (about 1 RecF monomer/4-6 base pairs) in the presence of adenosine 5'-O-(3-thio)triphosphate (ATP gamma S), forming a homogeneous protein coating on the DNA. Little or no cooperativity is evident in the(More)
RecA protein filaments formed on circular (ssDNA) in the presence of ssDNA binding protein (SSB) are generally stable as long as ATP is regenerated. On linear ssDNA, stable RecA filaments are believed to be formed by nucleation at random sites on the DNA followed by filament extension in the 5' to 3' direction. This view must now be enlarged as we(More)
The Escherichia coli RecF protein possesses a weak ATP hydrolytic activity. ATP hydrolysis leads to RecF dissociation from double-stranded (ds)DNA. The RecF protein is subject to precipitation and an accompanying inactivation in vitro when not bound to DNA. A mutant RecF protein that can bind but cannot hydrolyze ATP (RecF K36R) does not readily dissociate(More)
RecA protein forms filaments on both single- and double-stranded DNA. Several studies confirm that filament extension occurs in the 5' to 3' direction on single-stranded DNA. These filaments also disassemble in an end-dependent fashion, and several indirect observations suggest that the disassembly occurs on the end opposite to that at which assembly(More)
The RecX protein is a potent inhibitor of RecA protein activities. RecX functions by specifically blocking the extension of RecA filaments. In vitro, this leads to a net disassembly of RecA protein from circular single-stranded DNA. Based on multiple observations, we propose that RecX has a RecA filament capping activity. This activity has predictable(More)
KaiC from Synechococcus elongatus PCC 7942 (KaiC) is an essential circadian clock protein in cyanobacteria. Previous sequence analyses suggested its inclusion in the RecADnaB superfamily. A characteristic of the proteins of this superfamily is that they form homohexameric complexes that bind DNA. We show here that KaiC also forms ring complexes with a(More)
RecA protein promotes a substantial DNA strand exchange reaction in the presence of adenosine 5'-O-3-(thio)triphosphate (ATP gamma S) (Menetski, J.P., Bear, D.G., and Kowalczykowski, S.C. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 21-25), calling into question the role of ATP hydrolysis in the strand exchange reaction. Here, we demonstrate that the ATP gamma(More)
In the presence of both the RecF and RecR proteins, RecA filament extension from a single strand gap into adjoining duplex DNA is attenuated. RecR protein alone has no effect, and RecF protein alone has a reduced activity. The RecFR complexes bind randomly, primarily to the duplex regions of the DNA, and the extension of the RecA filament is halted at the(More)
A set of C-terminal deletion mutants of the RecA protein of Escherichia coli, progressively removing 6, 13, 17, and 25 amino acid residues, has been generated, expressed, and purified. In vivo, the deletion of 13 to 17 C-terminal residues results in increased sensitivity to mitomycin C. In vitro, the deletions enhance binding to duplex DNA as previously(More)