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DNA topology as a factor affecting transcription in bacteria
Hladíková, Kristýna ; Krásný, Libor (advisor) ; Nešvera, Jan (referee)
DNA topology plays a key role in regulation of gene expression by affecting interactions between DNA and RNA polymerase and other regulatory proteins. In this work, I review the process of transcription and selected mechanisms of its regulation, focusing on the effects of DNA topology. A key characteristic of DNA topology is the level of supercoiling. I describe how the DNA supercoiling influences initiation of transcription, and how it is affected by topoisomerases and nucleoid-associating proteins. I then discuss selected examples of regulation of gene expression by topology. Finally, I discuss the alternative σN factor from Bacillus subtilis, which allows more efficient transcription initiation from linear (i.e. relaxed) rather than supercoiled DNA templates. In this property, σN diametrically differs from other σ factors. Key words: DNA, topology, RNA polymerase, transcription, promoter, sigma factor
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