1. Studies on the size of the messenger-RNA transcribed from the histidine operon during simultaneous and sequential depression
- Author
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Pál Venetianer, Robert F. Goldberger, and Mary Anne Berberich
- Subjects
Genetics, Microbial ,Salmonella typhimurium ,Chemical Phenomena ,Operon ,Biology ,medicine.disease_cause ,Tritium ,Biochemistry, Genetics and Molecular Biology (miscellaneous) ,medicine ,Centrifugation, Density Gradient ,Histidine ,RNA, Messenger ,Gene ,Uridine ,Derepression ,chemistry.chemical_classification ,Messenger RNA ,Mutation ,Carbon Isotopes ,fungi ,Genetic code ,Chemistry ,Enzyme ,chemistry ,Biochemistry ,Genes ,Genetic Code ,Enzyme Repression ,Peptide Hydrolases - Abstract
The techniques of double isotope labeling and specific hybridization have been used to determine the size of the mRNA transcribed from the histidine operon in Salmonella typhimurium under conditions of derepression. The results obtained by both techniques agree with the previous results of Martin3 which demonstrated that, in a constitutive mutant, the histidine mRNA is polycistronic. Previous studies revealed that derepression of the enzymes for histidine biosynthesis may proceed by either of two modes1,2. One mode is characterized by simultaneous derepression of all the enzymes, whereas the other mode is characterized by the derepression of the enzymes in a temporal sequence which corresponds with the positional sequence of genes in the histidine operon. Since the present studies show that the mRNA transcribed from the histidine operon is always polycistronic, regardless of the mode of derepression, we may rule out the possibility that the difference between the two modes reflects any difference in the size of the histidine mRNA. Rather, the difference must lie in the manner in which the polycistronic histidine mRNA is translated.
- Published
- 1968