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Gene expression of the histidine operon
Acta Microbiologica Academiae Scientiarum Hungaricae
|January 1, 1976
Summary
Histidine biosynthesis in bacteria like Salmonella typhi-murium and Escherichia coli is controlled by two main processes: repression and feedback inhibition. These mechanisms, involving histidyl-transfer RNA and histidine itself, are interconnected and regulate the his operon.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Histidine biosynthesis is a fundamental metabolic pathway in bacteria.
- Regulation of this pathway is crucial for cellular homeostasis and survival.
- Key regulatory mechanisms include repression and feedback inhibition.
Purpose of the Study:
- To investigate the regulatory mechanisms of histidine biosynthesis in Salmonella typhi-murium and Escherichia coli.
- To elucidate the interplay between repression and feedback inhibition.
- To identify the role of the first biosynthetic enzyme in regulating the his operon.
Main Methods:
- Analysis of gene expression related to histidine biosynthesis.
- Enzyme activity assays.
- Studies on the effects of histidine and histidyl-tRNA levels.
Main Results:
- Histidine biosynthesis is regulated by both repression and feedback inhibition.
- Repression is mediated by the intracellular level of histidyl-transfer RNA (tRNA).
- Feedback inhibition involves histidine acting as an allosteric inhibitor of the first enzyme in the pathway.
Conclusions:
- The two regulatory processes, repression and feedback inhibition, are interconnected.
- The first enzyme in histidine biosynthesis plays a key role in regulating the his operon.
- Regulation appears to be primarily negative, though positive control cannot be ruled out.