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Carbon catabolite repression in Gram positive bacteria

Catabolite repression (CR) is evoked by the presence of a rapidly metabolizable carbon source in complex growth media and affects the industrial production by bacteria of enzymes, extracellular polysaccharides and secondary metabolites.
Research has involved identification and functional characterization of cis and trans acting elements as well as components of the phosphotransferase system involved in CR. The complete signalling pathway leading from the uptake of a metabolizable carbon source to reduced expression of catabolic genes has been unravelled.

The following 3 elements have been shown to be involved in CR of Gram positive bacteria:
mutations affecting CcpA, a presumed repressor;
mutations affecting Ser-46 of HPr, preventing the phosphorylation of this phosphocarrier protein and leading to the loss of CR of numerous catabolic enzymes;
mutations affecting the catabolite responsive element (CRE) of a certain catabolic gene leads to insensitivity towards CR of only the corresponding catabolic enzyme.
The above 3 elements have been shown to be involved in CR in bacilli, lactobacilli, streptococci and enterococi. A different CR mechanism has been suggested for Staphylococcus xylosus.

Reported by

Institut National de la Recherche Agronomique
78850 Thiverval-Grignon
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