engleski

Construction and characterization of streptomyces rimosus recA mutant: recA-deficient strain remains viable

Although previously reported attempts to construct recA null mutants in Streptomyces spp., were unsuccessful, we have used the suicidal plasmid pErmDRecA to inactivate the recA gene in Streptomyces rimosus by gene disruption. pErmDRecA carries the erythromycin resistance gene ermE and a 451 bp long DNA fragment from the S. rimosus recA gene (amino acids 2-151). An erythromycin resistant clone with single plasmid integration into the recA gene on chromosome was analyzed in details. This clone possesses one inactive copy of recA lacking the entire promoter region and ATG start codon and a second, truncated gene which encodes only first 151 amino acids of the RecA protein. This S. rimosus recA mutant can be therefore considered a completely RecA-deficient strain. The mutant strain is highly sensitive to the UV light. Introduction of a plasmid carrying the wild type S. rimosus recA gene completely restored UV resistance of the recA mutant. recA genes encoding RecA proteins with short deletions at the C-terminus (21 and 51 amino acids), when introduced in the same way, could not fully abolish UV sensitivity of the S. rimosus recA strain.

recA mutant ; Streptomyces ; gene disruption ; UV sensitivity

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