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Transcription activation of the BMR promoter of bacillus subtilis by BMRR

University of British Columbia

The bmr gene, encoding the Bacillus subtilis multidrug efflux protein Bmr, is positively regulated by the protein BmrR. In vivo, transcription of the bmr promoter occurs at a low, basal level in the absence of drug. When a drug substrate of Bmr such as rhodamine 6G is added to cells, transcription is enhanced approximately 18 fold from basal levels. In vitro characterization of BmrR and RNAP binding to the bmr promoter showed that RNAP did not bind to linear DNA fragments containing the promoter region unless BmrR was also present. Binding of both BmrR and RNAP was enhanced approximately 2 fold when rhodamine 6G was added. Using a supercoiled template, RNAP appeared to be able to bind on its own. Results from in vitro transcription assays indicated that RNAP was unable to transcribe a linear template containing the bmr promoter by itself. BmrR together with RNAP allowed a low level of transcription, and addition of rhodamine 6G enhanced transcription approximately 3 fold. On a supercoiled template, RNAP was capable of transcribing from the bmr promoter without BmrR, and BmrR itself did not enhance transcription unless rhodamine 6G was added. Thus, transcription enhancement in the presence of rhodamine 6G was likely due to enhanced binding of BmrR and RNAP.

Thesis/Dissertation

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2009-05-26

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http://hdl.handle.net/2429/8183

Microbiology and Immunology

University of British Columbia

UBCV

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