Related Experiment Videos
DNA sequence from the histidine operon control region: seven histidine codons in a row
Summary
Researchers sequenced DNA upstream of the histidine operon in Salmonella typhimurium. A leader sequence with a seven-histidine codon stretch suggests a novel regulatory mechanism for histidine operon control.
Area of Science:
- Molecular Biology
- Genetics
- Microbiology
Background:
- The histidine operon in Salmonella typhimurium is a key metabolic pathway.
- Understanding its regulation is crucial for bacterial physiology.
Purpose of the Study:
- To determine the DNA sequence preceding the first structural gene of the histidine operon.
- To identify potential regulatory elements controlling histidine operon expression.
Main Methods:
- Dideoxy chain-termination method for DNA sequencing.
- Construction of an M13-histidine transducing phage for single-stranded DNA template.
- In vitro recombination techniques.
Main Results:
- The DNA sequence of 250 base pairs upstream of the histidine operon was determined.
- The histidine leader RNA termination site was identified 47 nucleotides before the G gene start codon.
- A potential short protein-coding region with seven consecutive histidine codons was found in the leader RNA.
Conclusions:
- The identified leader sequence and polyhistidine tract suggest a novel mechanism for histidine operon regulation.
- Ribosome stalling at the histidine codon run is proposed as the primary control mechanism when histidine is scarce.