Reading_TwoComponentSystem - Two-Component Regulatory...

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Unformatted text preview: Two-Component Regulatory Systems & Environmental Sensing This lecture will focus on how two-component regulatory system control gene expression in bacteria and how these systems sense changes in the environment of the bacterium. In order to understand how these two-component regulatory systems can control gene expression, it is helpful to familiarize your self with more simple, one-component regulatory systems. Examples of these one-component regulatory systems are described in the follow section of the textbook. Textbook Reading Pages 356-357 “Negative Regulation” This should largely be review. The points to be remembered from this text: Be able to describe how a transcriptional repression prevents transcription of a gene. Know what is an operator site on DNA. Know how the activity of repressor proteins can be controlled by small molecules. Know what are the similarities of inducers and co-repressors. Know that some transcriptional regulators can act as repressors at some promoters and as activators at other promoters. Textbook Reading Pages 357-359 “Positive Regulation” The points to be remembered from this text: Know how interaction of transcriptional activators with promoter regions and RNA polymerase differs from transcriptional repressors. Know what the term “regulon” means. Know that small molecules can bind to and activate transcription activators. These small molecules are co-activators. Know how co-activators and co-repressors are similar, and how the activity of these molecules differs from an inducer. Know that some promoters can be regulated by both a transcriptional repressor and an activator. In this lecture, we will look at how two-component regulatory systems were identified. Specifically, how it was determined that the kinase component of the regulatory system covalently modified the transcription factor component of the system with phosphate. We will also look at how environment signals that control the kinase component have been identified. The following section of the textbook will familiarize you with the basic mechanism of action of the two-component regulatory systems. Textbook Reading Pages 359-360 “Regulation by Two-component Signal Transduction Pathways” The points to be remembered from this text: 1 Know that two-component regulatory systems are composed of at least two components, the kinase and the response regulator. Know that the kinase will covalently modify itself with phosphate using ATP as a phosphate donor. Know that this reaction is called “autophosphorylation”. Know that the phosphate on the kinase is transferred to the response regulator, resulting in its covalent modification by phosphate. Know that response regulators can be transcriptional activators or transcriptional repressors. Know that the activity of the kinase is regulated by an environmental signal. 2 ...
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