2003
DOI: 10.1074/jbc.m212916200
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Magnesium Ion-dependent Activation of the RecA Protein Involves the C Terminus

Abstract: Optimal conditions for RecA protein-mediated DNA strand exchange include 6 -8 mM Mg 2؉ in excess of that required to form complexes with ATP. We provide evidence that the free magnesium ion is required to mediate a conformational change in the RecA protein C terminus that activates RecA-mediated DNA strand exchange. In particular, a "closed" (low Mg 2؉ ) conformation of a RecA nucleoprotein filament restricts DNA pairing by incoming duplex DNA, although singlestranded overhangs at the ends of a duplex allow li… Show more

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Cited by 74 publications
(130 citation statements)
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“…SSB has multiple salt-dependent DNA binding modes (30,59) interaction site or sites on RecA protein outside of the C terminus that affect the capacity of RecA to displace SSB. In contrast, an interaction of Mg 2ϩ with these sites does not appear to be required for the strand exchange reaction, since the excess Mg 2ϩ requirement in that reaction was largely eliminated for RecA⌬C17 (44).…”
Section: Discussionmentioning
confidence: 93%
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“…SSB has multiple salt-dependent DNA binding modes (30,59) interaction site or sites on RecA protein outside of the C terminus that affect the capacity of RecA to displace SSB. In contrast, an interaction of Mg 2ϩ with these sites does not appear to be required for the strand exchange reaction, since the excess Mg 2ϩ requirement in that reaction was largely eliminated for RecA⌬C17 (44).…”
Section: Discussionmentioning
confidence: 93%
“…The truncated proteins dramatically alter the pH-reaction profile for DNA strand exchange (43) and exhibit a progressive reduction in the requirement for free Mg 2ϩ in the same reaction (44). For the RecA⌬C17 mutant protein, there is no measurable requirement for Mg 2ϩ in excess of that required to coordinate the ATP used in a given experiment (44). At Mg 2ϩ concentrations above their respective optima, reactions promoted by the mutant proteins are somewhat inhibited and produce DNA species that do not migrate into the gel.…”
mentioning
confidence: 99%
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“…The LexA repressor protein controls expression of the recA gene (15,16). The 17 C-terminal amino acids of RecA function in autoregulation of most protein activities (17)(18)(19). Finally, E. coli possesses many additional proteins that function as recombination regulators, with RecA as their target (20 -22).…”
mentioning
confidence: 99%
“…In addition, the initiation proteins (such as RecBCD and RecFOR) might interact directly with the RecA protein during the filament nucleation process, altering RecA conformation so that the C-terminus is no longer inhibitory. These data sets suggest that the DNA binding regulation ability of RecA and/or its ability to compete with SSB would allow RecA to gain access to SSB-coated DNA only at the appropriate time, such as after a replication fork stalls, and that the C-terminus acts as a regulatory switch, modulating the access of double-stranded DNA to the presynaptic filament, thereby inhibiting homologous DNA pairing and strand exchange at low magnesium ion concentrations (Eggler et al, 2003;Lusetti et al, 2003aLusetti et al, , 2003b. In MsRecA, the absence of the last 25 amino acids from the C-terminal domain (a region rich in negatively charged amino acids) could have implications for its functions since regulatory mechanisms, such as those described for EcRecA, can be affected.…”
mentioning
confidence: 99%