catabolite repression


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ca·tab·o·lite re·pres·sion

the decreased expression of an operon because of elevated levels of a catabolite of a biochemical pathway.

catabolite repression

REPRESSION of certain INDUCIBLE ENZYME systems by the presence of specific carbon sources, such as GLUCOSE, that the organism prefers to metabolize. For example, in bacteria, EXPRESSION of the LAC OPERON, concerned with the enzymes for the breakdown of LACTOSE, is repressed in the presence of glucose, even though inducers of the operon are available. When the glucose is used up, expression of the lactose operon can be induced. Catabolite repression is important to the efficient running of the cell, because glucose can be metabolized directly in GLYCOLYSIS without the need to expend energy inducing the synthesis of those enzymes required to metabolize the lactose. See also OPERON MODEL.
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Glucose and related sugars repress the transcription of genes required to utilize certain carbon sources such as xylan or cellulose by carbon catabolite repression (CCR) [13].
In this study mutagenesis approach was used to reduce the catabolite repression effects of simple sugar glucose.
These results might be attributed to the fact that the presence of readily available substrates has been noted to influence the biosynthesis of many extracellular enzymes via catabolite repression mechanism (Vijayaraghavan et al.
2001) reported carbon catabolite repression of the enzyme, as FFH production was checked by the presence of monosaccharides like glucose and fructose in the medium.
Afterwards, enzyme activity declined due to decrease in nutrients availability in the medium, or carbon catabolite repression, as the expression in yeast is checked by the presence of monosaccharides like glucose and fructose as reported by Samia (2008).
These results appear to support catabolite repression by glucose and sorbitol with prodigiosin production.
Effects of anaerobic regulatory mutations and catabolite repression on regulation of hydrogen metabolism and hydrogenase isoenzyme composition in Salmonella tyhimurium.
A multiplicity of potential carbon catabolite repression mechanisms in prokaryotic and eukaryotic microorganisms.
The inhibition of this synthesis is called catabolite repression (CR) and the abundance of glucose, glycerol or other readily found fermentable carbon sources inhibit this enzyme synthesis [5].
The biosynthesis of [alpha]-amylase in most species of the genus Bacillus is repressed by readily metabolizable substrates, especially glucose, by a mechanism of catabolite repression [22].
However, some catabolic genes like amyE and XynA are regulated by carbon catabolite repression instead of substrate induction.
Decrease in biomass with high xylose concentration may be due to catabolite repression during aerobic metabolism.