Biomaterial Database

Protein phosphorylation regulates transcription of the beta-glucoside utilization operon in E. coli. 1989

O Amster-Choder, and F Houman, and A Wright

Department of Molecular Biology and Microbiology, Tufts University Health Sciences Campus, Boston, Massachusetts 02111.

We have investigated the interaction between BglF and BglG, two proteins that regulate expression of the E. coli bgl operon. BglF is both a negative regulator of operon expression and a phosphotransferase involved in uptake of beta-glucosides. BglG is a positive regulator that functions as a transcriptional antiterminator. We show here that BglF is phosphorylated by the soluble components of the phosphotransferase system: Enzyme I, HPr, and the phosphate donor phosphoenolpyruvate. Phosphorylated BglF can then transfer phosphate either to beta-glucosides or to wild-type BglG. Mutant BglG derivatives, which give constitutive expression of the bgl operon, show little or no phosphorylation by BglF. Hence BglF exerts its negative effect on operon expression by phosphorylating BglG, blocking its action as an antiterminator. BglG is dephosphorylated only in the presence of both BglF and beta-glucosides. Based on these results, we propose the following mechanism: In the absence of beta-glucosides, BglG is phosphorylated by BglF and is inactive in antitermination. Addition of inducer stimulates BglF to dephosphorylate BglG, allowing BglG to function as a positive regulator of operon expression. Beta-Glucosides are then phosphorylated and transported into the cell by BglF.

UI	MeSH Term	Description	Entries
D009876	Operon	In bacteria, a group of metabolically related genes, with a common promoter, whose transcription into a single polycistronic MESSENGER RNA is under the control of an OPERATOR REGION.	Operons
D010750	Phosphoproteins		Phosphoprotein
D010766	Phosphorylation	The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety.	Phosphorylations
D011494	Protein Kinases	A family of enzymes that catalyze the conversion of ATP and a protein to ADP and a phosphoprotein.	Protein Kinase,Kinase, Protein,Kinases, Protein
D004926	Escherichia coli	A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.	Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
D005786	Gene Expression Regulation	Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control (induction or repression) of gene action at the level of transcription or translation.	Gene Action Regulation,Regulation of Gene Expression,Expression Regulation, Gene,Regulation, Gene Action,Regulation, Gene Expression
D005960	Glucosides	A GLYCOSIDE that is derived from GLUCOSE.	Glucoside
D006027	Glycosides	Any compound that contains a constituent sugar, in which the hydroxyl group attached to the first carbon is substituted by an alcoholic, phenolic, or other group. They are named specifically for the sugar contained, such as glucoside (glucose), pentoside (pentose), fructoside (fructose), etc. Upon hydrolysis, a sugar and nonsugar component (aglycone) are formed. (From Dorland, 28th ed; From Miall's Dictionary of Chemistry, 5th ed)	Glycoside
D001426	Bacterial Proteins	Proteins found in any species of bacterium.	Bacterial Gene Products,Bacterial Gene Proteins,Gene Products, Bacterial,Bacterial Gene Product,Bacterial Gene Protein,Bacterial Protein,Gene Product, Bacterial,Gene Protein, Bacterial,Gene Proteins, Bacterial,Protein, Bacterial,Proteins, Bacterial
D001692	Biological Transport	The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.	Transport, Biological,Biologic Transport,Transport, Biologic