Positive control of gene expression in procaryotes.
In procaryotes three types of control network are involved with the regulation of gene expression: global control networks, operon/single gene specific regulation and temporal control systems. The mechanisms used for positive control include the use of new components of the transcription apparatus such as new RNA polymerases and sigma factors, the use of activator proteins and the use of transcription antitermination systems. For the second two mechanisms, secondary negative control systems may also operate to regulate the activity of activator proteins and transcription antitermination factors. Thus, only very rarely is regulation achieved by just a simple positive control system. Positive control circuits allow tight regulation of gene expression that is fail-safe, in that most mutant changes will lead to the system becoming non-inducible rather than lead to constitutive gene expression.
Drew
R E
RE
Department of Biochemistry and Molecular Biology, University College London, England.
D012321:DNA-Directed RNA Polymerases / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D014158:Transcription, Genetic
D012321:DNA-Directed RNA Polymerases