Identification of the first functional toxin-antitoxin system in Streptomyces

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Toxin-antitoxin (TA) systems are prevalent in bacteria and archaea, regulating plasmid stability and gene expression.
• The YefM/YoeB family is a well-characterized class of TA systems, primarily studied in Escherichia coli.

Purpose of the Study:

• To describe the first functional toxin-antitoxin system identified in Streptomyces species.
• To characterize the YefM/YoeBsl system from Streptomyces lividans and compare it to its E. coli homolog.

Main Methods:

• Expression of Streptomyces YoeBsl toxin alone and co-expression with its antitoxin YefM in E. coli.
• Cloning of yoeBsl in multicopy and single copy in wild-type and mutant S. lividans strains.
• Purification of the S. lividans YefM/YoeBsl complex and DNA binding assays.
• In vivo analysis of yoeBsl expression effects on translation initiation in E. coli.

Main Results:

• Streptomyces YoeBsl toxin demonstrated lethal effects when expressed alone in E. coli, but was neutralized by co-expressed YefM.
• The toxic effect of YoeBsl was confirmed in both wild-type and mutant S. lividans strains.
• The purified YefM/YoeBsl complex specifically bound to its own promoter region.
• In vivo, YoeBsl inhibited translation initiation in E. coli by targeting mRNA downstream of the initiation codon.

Conclusions:

• A functional YefM/YoeB toxin-antitoxin system exists in Streptomyces lividans and S. coelicolor.
• The mechanism of action of Streptomyces YoeBsl is conserved and similar to that of E. coli YoeB, inhibiting translation initiation.