Recombinational repair and SOS response in a recA730 mutant of bacteria Escherichia coli

Šimatović, Ana (2015) Recombinational repair and SOS response in a recA730 mutant of bacteria Escherichia coli. Doctoral thesis, Faculty of Science > Department of Biology.

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Abstract

The RecA730 protein is able to nucleate itself onto single stranded DNA and suppress the recombinational defect of a recF mutant. By determining cell survival after UV and gamma irradiation and conjugational recombination proficiency, we concluded that this mutant could suppress the deficiency of cells lacking RecA loading functions from both pathways (RecBCD, RecFOR), as well as the helicase deficiency in the recB1080 recQ mutant. It could not suppress the absence of exonuclease functions from both pathways (RecBCD, RecJ). RecA filament formation and its role in recombination and DNA repair depends on the RecA protein's ability to bind and hydrolyze ATP. The addition of the recA730 mutation in the recA2201 mutant, which has the phenotype of the recA null mutant since it is not able to hydrolyze ATP, results in a conformational change that enables the double mutant recA730, 2201 to induce the SOS response. By determining the basal level of the SOS response and the level after introduction of a double strand break, we concluded that the SOS response in this double mutant depends on the RecBCD enzyme and that the high level of SOS response, observed in the single mutant recA730, depends on ATP hydrolysis. The addition of the recA730 mutation in the recA4159 mutant, for which is assumed that does not bind ATP, did not restore the SOS induction in the single mutant recA730. This indicates that the SOS induction in mutant recA730 is dependent on a conformational change caused by ATP binding. Similar results were obtained in a conjugational recombination assay. The results we obtained strongly suggest that binding and hydrolyzing ATP are crucial for recombinational repair of double strand breaks in the mutant recA730.

Item Type: Thesis (Doctoral thesis)
Keywords: Escherichia coli, homologous recombination, SOS response, recA730, recA730, 2201, recA730, 4159
Supervisor: Brčić-Kostić, Krunoslav
Date: 2015
Number of Pages: 128
Subjects: NATURAL SCIENCES > Biology
Divisions: Faculty of Science > Department of Biology
Depositing User: Silvana Šehić
Date Deposited: 06 Jul 2015 09:06
Last Modified: 06 Jul 2015 09:06
URI: http://digre.pmf.unizg.hr/id/eprint/4090

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