Insights into Transcriptional Repression of the Homologous Toxin-Antitoxin Cassettes yefM-yoeB and axe-txe

International Journal of Molecular Sciences

Katarzyna Potrykus¹  Barbara Kędzierska¹  Beata Wodzikowska¹  Agnieszka Szalewska-Pałasz¹ 

[1] Department of Bacterial Molecular Genetics, Faculty of Biology, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland;

关键词: transcription repression;    homologous toxin-antitoxin;    YefM-YoeB;    Axe-Txe;   

DOI  :  10.3390/ijms21239062

来源: DOAJ

【 摘 要 】

Transcriptional repression is a mechanism which enables effective gene expression switch off. The activity of most of type II toxin-antitoxin (TA) cassettes is controlled in this way. These cassettes undergo negative autoregulation by the TA protein complex which binds to the promoter/operator sequence and blocks transcription initiation of the TA operon. Precise and tight control of this process is vital to avoid uncontrolled expression of the toxin component. Here, we employed a series of in vivo and in vitro experiments to establish the molecular basis for previously observed differences in transcriptional activity and repression levels of the p_yy and p_at promoters which control expression of two homologous TA systems, YefM-YoeB and Axe-Txe, respectively. Transcriptional fusions of promoters with a lux reporter, together with in vitro transcription, EMSA and footprinting assays revealed that: (1) the different sequence composition of the −35 promoter element is responsible for substantial divergence in strengths of the promoters; (2) variations in repression result from the TA repressor complex acting at different steps in the transcription initiation process; (3) transcription from an additional promoter upstream of p_at also contributes to the observed inefficient repression of axe-txe module. This study provides evidence that even closely related TA cassettes with high sequence similarity in the promoter/operator region may employ diverse mechanisms for transcriptional regulation of their genes.

【 授权许可】

Unknown