The bgl sensory system: a transmembrane signaling pathway controlling transcriptional antitermination.
The bgl system represents a family of sensory systems composed of membrane-bound sugar-sensors and transcriptional antiterminators, which regulate expression of genes involved in sugar utilization in response to the presence of the corresponding sugar in the growth medium. The BglF sensor catalyzes different activities depending on its stimulation state: in its non-stimulated state, it phosphorylates the BglG transcriptional regulator, thus inactivating it; in the presence of the stimulating sugar, it transports the sugar and phosphorylates it and also activates BglG by dephosphorylation, leading to bgl operon expression. The sugar stimulates BglF by inducing a change in its membrane topology. BglG exists in several conformations: a dimer, which is active, and compact and non-compact monomers, which are inactive. BglF modulates the transition of BglG from one conformation to another, depending on sugar availability. The two Bgl proteins form a pre-complex at the membrane that dissociates upon stimulation, enabling BglG to exert its effect on transcription.
Amster-Choder
Orna
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Department of Molecular Biology, The Hebrew University, Hadassah Medical School, P.O.Box 12272, Jerusalem 91120, Israel. amster@cc.huji.ac.il
D000222:Adaptation, Physiological; D018407:Bacterial Physiological Phenomena; D001426:Bacterial Proteins / Q000502:physiology*; D050260:Carbohydrate Metabolism; D004926:Escherichia coli / Q000235:genetics / Q000502:physiology; D029968:Escherichia coli Proteins / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial; D008565:Membrane Proteins / Q000502:physiology*; D011494:Protein Kinases / Q000502:physiology*; D016601:RNA-Binding Proteins / Q000502:physiology*; D015398:Signal Transduction; D014158:Transcription, Genetic
D001426:Bacterial Proteins; C079638:BglF protein, E coli; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D016601:RNA-Binding Proteins; C064872:antiterminator proteins, Bacteria; D011494:Protein Kinases