Influence of RecA protein on induced mutagenesis

Blanco, Manuel; Herrera, Guadalupe; Collado, Pilar S.; Rebollo, José Emilio; Botella, Luisa María

doi:10.1016/s0300-9084(82)80102-8

Cited by 108 publications

(68 citation statements)

References 11 publications

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“…The recA142 mutant is recombination-deficient with partly intact protease-stimulating functions (Clark, 1973;Dutreix et al, 1985;Roberts & Roberts, 1981). The mutant displays UV-induced mutagenesis at a frequency lower than that observed for the WT (Blanco et al, 1982). Mutations in the recA gene that lead to recombination deficiency seem to be accompanied by alterations in protease function, i.e.…”

Section: Reorganization Depends On a Functional Reca Protein And Sos-mentioning

confidence: 99%

DNA compaction in the early part of the SOS response is dependent on RecN and RecA

Odsbu

Skarstad

2014

Microbiology

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The nucleoids of undamaged Escherichia coli cells have a characteristic shape and number, which is dependent on the growth medium. Upon induction of the SOS response by a low dose of UV irradiation an extensive reorganization of the nucleoids occurred. Two distinct phases were observed by fluorescence microscopy. First, the nucleoids were found to change shape and fuse into compact structures at midcell. The compaction of the nucleoids lasted for 10-20 min and was followed by a phase where the DNA was dispersed throughout the cells. This second phase lasted for~1 h. The compaction was found to be dependent on the recombination proteins RecA, RecO and RecR as well as the SOS-inducible, SMC (structural maintenance of chromosomes)-like protein RecN. RecN protein is produced in high amounts during the first part of the SOS response. It is possible that the RecN-mediated 'compact DNA' stage at the beginning of the SOS response serves to stabilize damaged DNA prior to recombination and repair.

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Section: Reorganization Depends On a Functional Reca Protein And Sos-mentioning

confidence: 99%

DNA compaction in the early part of the SOS response is dependent on RecN and RecA

Odsbu

Skarstad

2014

Microbiology

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“…Induced mutation frequencies are higher in strains expressing the muc and the rum operons rather than umuDC (4,5,23), an effect that has been ascribed in part to the greater susceptibility of MucA and RumA to proteolytic processing (20,23), although their relative ability to bind to a RecA-nucleoprotein filament also seems to be another mutagenically important phenotype (16,23). Different spectra of induced mutations have also been observed when mucAB has been substituted for umuDC (12,29).…”

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confidence: 99%

Substitution of mucAB or rumAB for umuDC alters the relative frequencies of the two classes of mutations induced by a site-specific T-T cyclobutane dimer and the efficiency of translesion DNA synthesis

1996

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We have examined the effect of replacing umuDC with mucAB or rumAB on the mutagenic properties of a T-T cyclobutane dimer in an attempt to determine the molecular basis for the differences in UV-induced mutagenesis that are associated with these structurally and functionally related genes. A single-stranded vector carrying a site-specific T-T cis-syn cyclobutane dimer was transfected into a set of isogenic Escherichia coli ⌬umuDC strains harboring low-copy-number plasmids expressing UmuDC, MucAB, RumAB, or their genetically engineered and mutagenically active counterparts UmuDC, MucAB, and RumAB, respectively. Although the overall mutation frequency was similar for all strains, the relative frequencies of the two classes of mutation induced by the T-T dimer varied according to the mutagenesis operon expressed. In umuDC strains, 3 T3A mutations outnumbered 3 T3C mutations, but the reverse was true for the mucAB and rumAB strains. We also found that the T-T dimer was bypassed with differing efficiencies in unirradiated cells expressing wild-type UmuDC, MucAB, and RumAB proteins. These differences can probably be attributed to the relative efficiency of the normal cellular posttranslational activation of UmuD, MucA, and RumA, respectively, since recombinant constructs expressing the mutagenically active UmuDC, MucAB, and RumAB proteins all promoted similarly high levels of bypass in UV-irradiated cells. These results suggest that the UmuD/UmuC complex and its homologs may differ in their relative abilities to promote elongation from T ⅐ T and T ⅐ G mismatched termini. Alternatively, they may differentially influence the efficiency with which these mismatches are edited or influence nucleotide insertion by the catalytic subunit of the DNA polymerase III.Efficient translesion synthesis and DNA damage-induced mutagenesis in Escherichia coli is known, in most cases, to require the function of the umuDC operon or one of its structural and functional homologs such as mucAB and rumAB (17,28,41). Each of these mutagenesis operons possesses a lexArepressible promoter, is regulated as part of the SOS response, and promotes mutagenesis induced by many types of DNA damage. Similarly, each operon (umuDC, mucAB, or rumAB) can promote mutagenesis only if the UmuD-like protein is proteolytically processed via a RecA-mediated self-cleavage reaction generating the mutagenically active UmuDЈ-like polypeptides such as UmuDЈ, MucAЈ, and RumAЈ, respectively (10,20,23,29,33). Activity also requires the formation of a complex consisting of a homodimer of the processed UmuDЈ-like polypeptide and a single molecule of its cognate UmuClike partner (i.e., UmuC, MucB, and RumB, respectively) (40).This complex is believed to bind to the DNA lesion at the blocked replication fork and facilitate translesion synthesis by DNA polymerase III (1,16,31,35). It has been hypothesized that translesion bypass occurs as a two-step process, in which the first step is a RecA-mediated insertion of a nucleotide opposite the lesion (a misincorporation in the cas...

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“…mucAB also restores inducible mutagenesis to normally nonmutable recA430 and lexA4(Ind-) strains of E. coli (6,7,29,31,57). In this report, we demonstrate that mucAB can also restore mutability to recA433 and recA435 strains.…”

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confidence: 99%

The enhanced mutagenic potential of the MucAB proteins correlates with the highly efficient processing of the MucA protein

et al. 1992

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Inducible mutagenesis in Escherichia coli requires the direct action of the chromosomally encoded UmuDC proteins or functional homologs found on certain naturally occurring plasmids. Although structurally similar, the five umu-like operons that have been characterized at the molecular level vary in their ability to enhance cellular and phage mutagenesis; of these operons, the mucAB genes from the N-group plasmid pKM101 are the most efficient at promoting mutagenesis. During the mutagenic process, UmuD is posttranslationally processed to an active form, UmuD'. To explain the more potent mutagenic efficiency of mucAB compared with that of umuDC it has been suggested that unlike UmuD, intact MucA is functional for mutagenesis. To examine this possibility, we have overproduced and purified the MucA protein. Although functionally similar to UmuD, MucA was cleaved much more rapidly both in vitro and in vivo than UmuD. In vivo, restoration of mutagenesis functions to normally nonmutable recA430, recA433, recA435, or recA730 A(umuDC)595::cat strains by either MucA+ or mutant MucA protein correlated with the appearance of the cleavage product, MucA'. These results suggest that most of the differences in mutagenic phenotype exhibited by MucAB and UmuDC correlate with the efficiency of posttranslational processing of MucA and UmuD rather than an inherent activity of the unprocessed proteins.

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Influence of RecA protein on induced mutagenesis

Cited by 108 publications

References 11 publications

DNA compaction in the early part of the SOS response is dependent on RecN and RecA

DNA compaction in the early part of the SOS response is dependent on RecN and RecA

Substitution of mucAB or rumAB for umuDC alters the relative frequencies of the two classes of mutations induced by a site-specific T-T cyclobutane dimer and the efficiency of translesion DNA synthesis

The enhanced mutagenic potential of the MucAB proteins correlates with the highly efficient processing of the MucA protein

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