Full text loading...
Chapter 1 : Regulation of Bacterial Transcription by Anti-σ Factors
Category: Microbial Genetics and Molecular Biology; Bacterial Pathogenesis
Ebook: Choose a downloadable PDF or ePub file. Chapter is a downloadable PDF file. File must be downloaded within 48 hours of purchase
In bacteria, gene expression is regulated primarily at the step of transcription initiation. The DNA-dependent RNA polymerase (RNAP), the central enzyme of transcription, comprises an evolutionarily conserved, 400-kDa catalytic core of five subunits (a2β β'ω). The transcription cycle begins when the σ factor associates with core RNAP to form the holoenzyme, which then locates promoters through sequence-specific interactions between elements of σ and the promoter DNA. The studies described in this chapter were performed with group 1, or primary, σ factors, which transcribe genes necessary for exponential growth under favorable conditions. The chapter focuses on cognate anti-σ/σ pairs for which structural studies have provided insights into function and regulation. A signal transduction pathway involving ECF σ factors related to Escherichia coli σE plays an important role in pathogenesis in some organisms. The evolution of structurally and functionally diverse anti-σ factors provide much more flexibility for the regulation of transcription initiation. Thus, the authors propose that the functional and structural diversity of anti-σ factors reflects the need for bacteria to relay a wide variety of environmental cues to the core transcriptional apparatus via regulation of the structurally conserved σ factors.