engleski

RecX protein from Streptomyces rimosus

The recX gene of Streptomyces rimosus has been identified downstream of the recA gene, cloned and sequenced. The amino acid sequence of the RecX protein is highly homologous to RecX proteins from other Streptomyces species. Short intergenic region between recA and recX genes has no potential promoter or terminator structure. Using reverse transcription and polymerase chain reactions we demonstrated that recX is cotranscribed with the recA gene. Consequently, recX expression is induced upon UV irradiation together with recA, and therefore recX is an SOS response gene. Purified S. rimosus RecX protein possesses DNA-binding potential and binds to both circular and linear double-stranded DNA as well as to circular single-stranded DNA. Protein dot blot analysis demonstrated direct physical interaction between RecA and RecX proteins in vitro. When S. rimosus RecA protein binds to DNA, all RecA-DNA complexes are in form of big aggregates which can not be analyzed in agarose gel. In the presence of RecX protein we observed appearance of defined nucleoprotein complexes, so we suggest the role of streptomycete RecX to enhance DNA-binding activity of RecA and to assist RecA in formation of proper nucleoprotein filament.

RecX; RecA; Streptomyces rimosus

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