title: Survival and SOS response induction in ultraviolet B irradiated Escherichia coli cells with defective repair mechanisms.
abstract: Purpose In this paper, the contribution of different genes involved in DNA repair for both survival and SOS induction in Escherichia coli mutants exposed to ultraviolet B radiation (UVB, [wavelength range 280-315 nm]) was evaluated. Materials and methods E. coli strains defective in uvrA, oxyR, recO, recN, recJ, exoX, recB, recD or xonA genes were used to determine cell survival. All strains also had the genetic sulA::lacZ fusion, which allowed for the quantification of SOS induction through the SOS Chromotest. Results Five gene products were particularly important for survival, as follows: UvrA > RecB > RecO > RecJ > XonA. Strains defective in uvrA and recJ genes showed elevated SOS induction compared with the wild type, which remained stable for up to 240 min after UVB-irradiation. In addition, E. coli strains carrying the recO or recN mutation showed no SOS induction. Conclusions The nucleotide excision and DNA recombination pathways were equally used to repair UVB-induced DNA damage in E. coli cells. The sulA gene was not turned off in strains defective in UvrA and RecJ. RecO protein was essential for processing DNA damage prior to SOS induction. In this study, the roles of DNA repair proteins and their contributions to the mechanisms that induce SOS genes in E. coli are proposed.
authors.affiliation: a Laboratorio de Microbiología y Mutagénesis Ambiental, Grupo de Investigaciòn en Microbiología y Genética, Escuela de Biología , Universidad Industrial de Santander , Bucaramanga , Colombia ;
authors.forename: Cesar Augusto
authors.initials: CA
authors.lastname: Prada Medina
authors.affiliation: a Laboratorio de Microbiología y Mutagénesis Ambiental, Grupo de Investigaciòn en Microbiología y Genética, Escuela de Biología , Universidad Industrial de Santander , Bucaramanga , Colombia ;
authors.forename: Elke Tatjana
authors.initials: ET
authors.lastname: Aristizabal Tessmer
authors.affiliation: a Laboratorio de Microbiología y Mutagénesis Ambiental, Grupo de Investigaciòn en Microbiología y Genética, Escuela de Biología , Universidad Industrial de Santander , Bucaramanga , Colombia ;
authors.forename: Nathalia
authors.initials: N
authors.lastname: Quintero Ruiz
authors.affiliation: b Departamento de Biología , Instituto Nacional de Investigaciones Nucleares , Distrito Federal , México.
authors.forename: Jorge
authors.initials: J
authors.lastname: Serment-Guerrero
authors.affiliation: a Laboratorio de Microbiología y Mutagénesis Ambiental, Grupo de Investigaciòn en Microbiología y Genética, Escuela de Biología , Universidad Industrial de Santander , Bucaramanga , Colombia ;
authors.forename: Jorge Luis
authors.initials: JL
authors.lastname: Fuentes
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D002470:Cell Survival / Q000502:physiology / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D004926:Escherichia coli / Q000166:cytology / Q000502:physiology* / Q000528:radiation effects*; D011829:Radiation Dosage; D013014:SOS Response, Genetics / Q000502:physiology* / Q000528:radiation effects*; D014466:Ultraviolet Rays
chemical_list: D001426:Bacterial Proteins
keywords: DNA repair genes; Escherichia coli; SOS induction; UVB radiation