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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)
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)
When DinI is present at concentrations that are stoichiometric with those of RecA or somewhat greater, DinI has a substantial stabilizing effect on RecA filaments bound to DNA. Exchange of RecA between free and bound forms was almost entirely suppressed, and highly stable filaments were documented with several different experimental methods. DinI-mediated(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)
Deinococcus radiodurans exhibits an extraordinary resistance to the effects of exposure to ionizing radiation (IR). DdrB is one of five proteins induced to high levels in Deinococcus following extreme IR exposure and that play a demonstrable role in genome reconstitution. Although homology is limited, DdrB is a bacterial single-stranded DNA-binding protein.(More)
Xp10 is a lytic bacteriophage of the phytopathogenic bacterium Xanthomonas oryzae. Though morphologically Xp10 belongs to the Syphoviridae family, it encodes its own single-subunit RNA polymerase characteristic of T7-like phages of the Podoviridae family. Here, we report the determination and analysis of the 44,373 bp sequence of the Xp10 genome. The genome(More)
Replication forks often stall or collapse when they encounter a DNA lesion. Fork regression is part of several major paths to the repair of stalled forks, allowing nonmutagenic bypass of the lesion. We have shown previously that Escherichia coli RecA protein can promote extensive regression of a forked DNA substrate that mimics a possible structure of a(More)
The process of bacterial conjugation involves the transfer of a conjugative plasmid as a single strand. The potentially deleterious SOS response, which is normally triggered by the appearance of single-stranded DNA, is suppressed in the recipient cell by a conjugative plasmid system centered on the product of the psiB gene. The F plasmid PsiB protein(More)
The RecA residues Lys248 and Glu96 are closely opposed across the RecA subunit-subunit interface in some recent models of the RecA nucleoprotein filament. The K248R and E96D single mutant proteins of the Escherichia coli RecA protein each bind to DNA and form nucleoprotein filaments but do not hydrolyze ATP or dATP. A mixture of K248R and E96D single mutant(More)