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RecA/SOS response

See also Pyrimidine Dimers, Thymine Dimers Photoreactivation, Postreplication Repair, RecA / SOS Response, Antioxidants (from Chapter 15), Oxygen Metabolism and Human Disease... [Pg.1167]

See also Recombination Repair, RecA/SOS Response, SOS Regulon... [Pg.1350]

See also Recombination, Homologous Recombination, RecA / SOS Response... [Pg.1903]

Mutations in either recA or lexA can abolish the SOS-response and eliminate both W-reactivation and W-mutagenesis. These mutations also eliminate the mutability of the bacteria by UV-irradiation (16) The observation that UV mutagenesis depended on the SOS-response established that mutations were not inevitable outcomes of DNA damage and that DNA damage required processing by cellular mechanisms in order for mutations to be recovered. What specific processes regulated by the SOS-response are responsible for mutagenesis ... [Pg.331]

Figure 22.22. SOS response in E. coli. Under normal growth conditions (SOS off), genes under the SOS control are repressed by the LexA repressor. DNA damage or replication block triggers SOS response, leading to activation of the RecA co-protease and subsequent inactivation of the LexA repressor by RecA-assisted auto cleavage. This results in induced transcription of the various SOS genes (SOS on). Combined cellular activities such as DNA repair and translesion synthesis eventually removes the SOS signal. Consequently, the RecA co-protease is inactivated and the LexA repressor is accumulated in cells, returning cells to the SOS off state. Figure 22.22. SOS response in E. coli. Under normal growth conditions (SOS off), genes under the SOS control are repressed by the LexA repressor. DNA damage or replication block triggers SOS response, leading to activation of the RecA co-protease and subsequent inactivation of the LexA repressor by RecA-assisted auto cleavage. This results in induced transcription of the various SOS genes (SOS on). Combined cellular activities such as DNA repair and translesion synthesis eventually removes the SOS signal. Consequently, the RecA co-protease is inactivated and the LexA repressor is accumulated in cells, returning cells to the SOS off state.
Pol V is upregulated from <15 to 200 copies per cell approximately 45 minutes after SOS induction. Pol V is a heterotrimer with a subunit composition of UmuD 2C (see Fig. 6a). UmuC contains the catalytic domain of Pol V. UmuD is the product of RecA-mediated proteolytic cleavage of UmuD. Importantly, Pol V function requires RecA, and the mechanism by which RecA stimulates Pol V activity has been under investigation for several years (57). Recent data indicate that RecA nucleoprotein filaments act in trans to stimulate Pol V (see Fig. 6a) (57, 58). Interestingly, RecA hlaments in cis (immediately 5 to Pol V on the DNA template) do not stimulate Pol V (59). Pol V and SSB may cooperate to displace RecA from DNA (57, 60). Alternatively, recent data indicate that RecA may be removed by UvrD helicase, as UvrD is also induced during the SOS response, but whether UvrD plays a direct role in translesion synthesis is currently an open question (61, 62). [Pg.79]

RecA is a genetic regulator, activating the synthesis of many proteins (including DNA repair proteins) that help a bacterium adapt to a variety of metabolic stresses. This adaptation is called the SOS response. The transcriptional activations and a fuller description of the SOS response are presented here... [Pg.1362]

RecA - A multifunctional protein with Mr of about 38,000. In recombination it promotes the pairing of homologous strands. In the SOS response it also plays a role in gene activation. Figure 25.23... [Pg.1885]

Similar to its role in controlling SOS response after DNA damage, a second means of regulation by RecA in prokaryotic PRR also involves the... [Pg.280]

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SOS response

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