Maltose permease

In addition to acting as a catabolite repressor, glucose (or its catabolites) may also act as a catabolite inactivator. Catabolite inactivation describes a rapid disappearance of enzyme activity, in contrast to the diluting out which follows catabolite repression, when the cells continue to multiply. Maltose permease is inactivated by this process, which is probably the result of proteolytic enzyme action [30]. 

The half-life of maltose permease is approximately 1 2 hr [19], therefore in (/) the presence of repressing concentrations of glucose, ( ) the absence of inducing concentrations of maltose or (///) the absence of protein synthesis, the level of permease will fall by 90 % in some 5 hr. 

S. F. Permuth, and R. J. Brooker, Isolation and characterization of lactose permease mutants with an enhanced recognition of maltose and diminished recognition of cellobiose, J. Biol. Chem. 264 14698, 1989.)... 

The uptake of maltose and maltotriose is mediated by specific inducible permeases [20, 21], A coordinated induction of an a-glucosidase (maltase) also occurs, so that on entering the cell both sugars are hydrolyzed to glucose [22,23]. Neither the permeases nor the maltase are synthesized in the presence of glucose (>0 4% w/v for brewing yeasts [24]) and hence are said to be catabolite repressed [25]. 

The fermentation of maltose is known in lactococci the permease system is active (Sjoberg and Hahn-Hagerdahl 1989), while in various strains of L. sanfranciscensis, maltose is converted to glucose-1-phosphate and glucose (von Wright and Axelsson 2012). 

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