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Regulation of lactose-phosphoenolpyruvate-dependent phosphotransferase system and beta-D-phosphogalactoside galactohydrolase activities in Lactobacillus casei. 1983

B M Chassy, and J Thompson

The lactose-phosphoenolpyruvate-dependent phosphotransferase system (lac-PTS) and beta-D-phosphogalactoside galactohydrolase (P-beta-gal) mediate the metabolism of lactose by Lactobacillus casei. Starved cells of L. casei contained a high intracellular concentration of phosphoenolpyruvate, and this endogenous energy reserve facilitated characterization of phosphotransferase system activities in physiologically intact cells. Data obtained from transport studies with whole cells and from in vitro phosphotransferase system assays with permeabilized cells revealed that the lac-PTS had a high affinity for beta-galactosides (e.g., lactose, lactulose, lactobionic acid, and arabinosyl-beta-D-galactoside). lac-PTS and P-beta-gal activities were determined in wild-type strains and strains defective in the glucose-phosphoenolpyruvate-dependent phosphotransferase system after growth on various sugars and in the presence of potential inducers. We found that (i) the lac genes (i.e., the genes coding for the lac-PTS proteins and P-beta-gal) were induced by metabolizable and non-metabolizable beta-galactosides (presumably acting as their phosphorylated derivatives), (ii) galactose 6-phosphate was not an inducer in most strains, (iii) the ratio of lac-PTS activity to P-beta-gal activity in a given strain was not constant, and (iv) inhibition of lac gene expression during growth on glucose was a consequence of glucose-phosphoenolpyruvate-dependent phosphotransferase system-mediated inducer exclusion, repressive effects of a functional glucose-phosphoenolpyruvate-dependent phosphotransferase system and glucose-derived metabolites. The expression of the lac-PTS structural genes and the expression of the P-beta-gal gene are independently regulated and may be subject to both positive control and negative control.

UI MeSH Term Description Entries
D007780 Lacticaseibacillus casei A rod-shaped bacterium isolated from milk and cheese, dairy products and dairy environments, sour dough, cow dung, silage, and human mouth, human intestinal contents and stools, and the human vagina. L. casei is CATALASE positive. Lactobacillus casei
D007785 Lactose A disaccharide of GLUCOSE and GALACTOSE in human and cow milk. It is used in pharmacy for tablets, in medicine as a nutrient, and in industry. Anhydrous Lactose,Lactose, Anhydrous
D010731 Phosphoenolpyruvate Sugar Phosphotransferase System The bacterial sugar phosphotransferase system (PTS) that catalyzes the transfer of the phosphoryl group from phosphoenolpyruvate to its sugar substrates (the PTS sugars) concomitant with the translocation of these sugars across the bacterial membrane. The phosphorylation of a given sugar requires four proteins, two general proteins, Enzyme I and HPr and a pair of sugar-specific proteins designated as the Enzyme II complex. The PTS has also been implicated in the induction of synthesis of some catabolic enzyme systems required for the utilization of sugars that are not substrates of the PTS as well as the regulation of the activity of ADENYLYL CYCLASES. EC 2.7.1.-. Phosphoenolpyruvate Hexose Phosphotransferases,Phosphoenolpyruvate-Glycose Phosphotransferase System,Hexose Phosphotransferases, Phosphoenolpyruvate,Phosphoenolpyruvate Glycose Phosphotransferase System,Phosphotransferase System, Phosphoenolpyruvate-Glycose,Phosphotransferases, Phosphoenolpyruvate Hexose,System, Phosphoenolpyruvate-Glycose Phosphotransferase
D004790 Enzyme Induction An increase in the rate of synthesis of an enzyme due to the presence of an inducer which acts to derepress the gene responsible for enzyme synthesis. Induction, Enzyme
D005690 Galactose An aldohexose that occurs naturally in the D-form in lactose, cerebrosides, gangliosides, and mucoproteins. Deficiency of galactosyl-1-phosphate uridyltransferase (GALACTOSE-1-PHOSPHATE URIDYL-TRANSFERASE DEFICIENCY DISEASE) causes an error in galactose metabolism called GALACTOSEMIA, resulting in elevations of galactose in the blood. D-Galactose,Galactopyranose,Galactopyranoside,D Galactose
D005696 Galactosidases A family of galactoside hydrolases that hydrolyze compounds with an O-galactosyl linkage. EC 3.2.1.-. Galactosidase
D005697 Galactosides Glycosides formed by the reaction of the hydroxyl group on the anomeric carbon atom of galactose with an alcohol to form an acetal. They include both alpha- and beta-galactosides.
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
D005796 Genes A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms. Cistron,Gene,Genetic Materials,Cistrons,Genetic Material,Material, Genetic,Materials, Genetic
D006026 Glycoside Hydrolases Any member of the class of enzymes that catalyze the cleavage of the glycosidic linkage of glycosides and the addition of water to the resulting molecules. Endoglycosidase,Exoglycosidase,Glycohydrolase,Glycosidase,Glycosidases,Glycoside Hydrolase,Endoglycosidases,Exoglycosidases,Glycohydrolases,Hydrolase, Glycoside,Hydrolases, Glycoside

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