ISSN:
0749-503X
Keywords:
δ-Aminolevulinate synthase
;
δ-aminoleuvulinate dehydratase
;
Saccharomyces cerevisiae HEM R+ mutants
;
catabolite repression and derepression
;
Life and Medical Sciences
;
Genetics
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
Notes:
Catabolite repression and derepression on δ-aminolevulinate synthase (ALA-S) and δ-aminolevulinate dehydratase (ALA-D) in a normal yeast strain, D27, and its derived D27/C6 (HEM R+) were investigated. ALA-S and ALA-D activities and intracellular ALA (I-ALA) at different physiological states of the cells were measured. In YPD medium, under conditions of repression and when glucose was exhausted, both strains behaved identically as if the mutation was not expressed. In YPEt medium, however, both ALA-S and ALA-D activities were higher than in YPD, but the I-ALA content and the enzymic activity profiles shown by the two strains were quite different. It appears, therefore, that the mutation causes a deregulation of ALA-S, so that its activity is kept at a high level throughout the cell cycle. This would explain the increased levels of cytochromes present in the mutant. This mutation may affect some regulatory aspect of ALA formation and renders an ALA-S of high activity; moreover, this enzyme species seems to be more stable than in the normal strain.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/yea.320090207
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