Transcriptional and mutational analyses of the Streptomyces lividans recX gene and its interference with RecA activity

Silke Vierling, Tilmann Weber, W. Wohlleben, G. Muth

Research output: Contribution to journalJournal articleResearchpeer-review


The role of the 20,922-Da RecX protein and its interference with RecA activity were analyzed in Streptomyces lividans. The recX gene is located 220 bp downstream of recA. Transcriptional analysis by reverse transcriptase PCR demonstrated that recX and recA constitute an operon. While recA was transcribed at a basal level even under noninducing conditions, a recA-recX cotranscript was only detectable after induction of recA following DNA damage. The recA-recX cotranscript was less abundant than the recA transcript alone. The recX gene was inactivated by gene replacement. The resulting mutant had a clearly diminished colony size, but was not impaired in recombination activity, genetic instability, and resistance against UV irradiation. Expression of an extra copy of the S. lividans recA gene under control of the thiostrepton-inducible tipA promoter was lethal to the recX mutant, demonstrating that RecX is required to overcome the toxic effects of recA overexpression. Since inactivation of the recX gene did not influence transcription of recA, the putative function of the RecX protein might be the downregulation of RecA activity by interaction with the RecA protein or filament
Original languageEnglish
JournalJournal of Bacteriology
Pages (from-to)4005-4011
Number of pages7
Publication statusPublished - 2000
Externally publishedYes


  • activity analysis Bacterial Proteins copy cytology DNA DNA Mutational Analysis Dose-Response Relationship,Radiation Down-Regulation drug effects expression function gene Gene Expression Regulation,Bacterial Genes,Bacterial genetic instability genetics instability metabolism Methyl Methanesulfonate Mutagenesis Mutagens mutant Operon overexpression PCR pharmacology Phenotype promoter protein Proteins radiation effects Radiation Tolerance Rec A Recombinases Recombination,Genetic replacement Research Support,Non-U.S.Gov't resistance Streptomyces Streptomyces lividans transcription Transcription,Genetic Ultraviolet Rays


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