Mechanism of suppression in Drosophila: regulation of tryptophan oxygenase by the su(s)+ allele

The suppressor gene, su(s)2, in Drosophila melanogaster restores the production of red and brown eye pigments for some purple and vermilion mutant alleles, respectively. We showed previously that the product of the su(s)+ allele caused inhibition of the sepiapterin synthase A produced by the purple...

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Bibliographic Details
Published in:Biochemical genetics 1987-06, Vol.25 (5/6), p.359-374
Main Authors: Yim, J.J, Yoon, J, Park, Y.S, Grell, E.H, Jacobson, K.B
Format: Article
Language:English
Subjects:
Alleles
Amino Acids - biosynthesis
Animals
Diet
DROSOPHILA
DROSOPHILA MELANOGASTER
Drosophila melanogaster - enzymology
Drosophila melanogaster - genetics
EYES
GENE
GENES
GENOMAS
GENOME
GENOMES
OEIL
OJOS
Oxazines - biosynthesis
OXIDOREDUCTASES
OXIDORREDUCTASAS
OXYDOREDUCTASE
PIGMENT
PIGMENTOS
PIGMENTS
Pigments, Biological
Protein Processing, Post-Translational
Suppression, Genetic
Tryptophan Oxygenase - antagonists & inhibitors
Tryptophan Oxygenase - genetics
Xanthenes
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Summary:The suppressor gene, su(s)2, in Drosophila melanogaster restores the production of red and brown eye pigments for some purple and vermilion mutant alleles, respectively. We showed previously that the product of the su(s)+ allele caused inhibition of the sepiapterin synthase A produced by the purple mutant but did not affect the wild-type enzyme. Suppression was accomplished by removing su(s)+ from the genome. We now report that the tryptophan oxygenase, produced by suppressible vermilion alleles, is also inhibited by extracts from su(s)+ flies. The inhibition of the vermilion enzyme can be reduced or eliminated, respectively, by prior storage of the extract at 4 or -20 degrees C or by boiling, whereas the wild-type enzyme is not affected by extracts of su(s)+ flies. Also, when the suppressible vermilion strain is raised on certain diets, brown eye pigment production occurs. This epigenetic suppression was reduced by the presence of an extra copy of su(s)+ in the genome. These data support a posttranslational mechanism for regulation of enzyme activity in which the activity of the mutant enzyme is reduced by the product of the su(s)+ allele. How the su(s)+ gene product can distinguish between the normal and the mutant forms of these two enzymes is discussed, along with other mechanisms for suppression that are currently under investigation.
ISSN:0006-2928
1573-4927
DOI:10.1007/BF00554545