Regulation of glucose metabolism in bacterial systems

Abstract

In the past 10 years there have been rapid developments in the elucidation of the mechanisms of the Pasteur (or oxygen) and the Crabtree (or glucose repression of the respiratory chain) Effects in bacterial systems, which convincingly exhibit the difference between the regulatory mechanisms in yeast and bacteria. The presented review will demonstrate that the enzyme phosphofructokinase plays no role in the mechanism of the Pasteur effect and that there exists no glucose repression on biomass formation in bacteria under aerobic conditions. Endproduct formation is caused aerobically and anaerobically by an oversupply of NADHP2, whereas biomass correlates to energy supply. This development indicates very strongly that the mechanism of the Pasteur effect may be reflected solely in the change of glucose uptake rates and must therefore be sought at the cell membrane. In regard to the Crabtree Effect, the question arises whether there exists such a mechanism in bacteria. The variability of the bacterial electron transport systems, the lack of cytochrome a as terminal oxidase together with bioenergetic investigations indicate that the Crabtree effect may give cause for an alteration but not for a cessation of respiratory activity.