Tryptophan operon leader
Encyclopedia
The Tryptophan operon leader is an RNA element
found at the 5' of some bacterial tryptophan operons
. The leader sequence can assume two different secondary structures known as the terminator and the anti-terminator structure. The leader also codes for very short peptide sequence that is rich in Tryptophan. The terminator structure is recognised as a termination signal for RNA polymerase
and the operon is not transcribed. This structure forms when the cell has an excess of tryptophan and ribosome
movement over the leader transcript is not impeded. When there is a deficiency of the charged tryptophanyl tRNA the ribosome translating the leader peptide stalls and the antiterminator structure can form. This allows RNA polymerase
to transcribe the operon.
At least 6 different amino acid operons are known to be regulated by this attenuation.
Cis-regulatory element
A cis-regulatory element or cis-element is a region of DNA or RNA that regulates the expression of genes located on that same molecule of DNA . This term is constructed from the Latin word cis, which means "on the same side as". These cis-regulatory elements are often binding sites for one or...
found at the 5' of some bacterial tryptophan operons
Trp operon
Trp operon is an operon - a group of genes that are used, or transcribed, together - that codes for the components for production of tryptophan. The Trp operon is present in many bacteria, but was first characterized in Escherichia coli. It is regulated so that when tryptophan is present in the...
. The leader sequence can assume two different secondary structures known as the terminator and the anti-terminator structure. The leader also codes for very short peptide sequence that is rich in Tryptophan. The terminator structure is recognised as a termination signal for RNA polymerase
RNA polymerase
RNA polymerase is an enzyme that produces RNA. In cells, RNAP is needed for constructing RNA chains from DNA genes as templates, a process called transcription. RNA polymerase enzymes are essential to life and are found in all organisms and many viruses...
and the operon is not transcribed. This structure forms when the cell has an excess of tryptophan and ribosome
Ribosome
A ribosome is a component of cells that assembles the twenty specific amino acid molecules to form the particular protein molecule determined by the nucleotide sequence of an RNA molecule....
movement over the leader transcript is not impeded. When there is a deficiency of the charged tryptophanyl tRNA the ribosome translating the leader peptide stalls and the antiterminator structure can form. This allows RNA polymerase
RNA polymerase
RNA polymerase is an enzyme that produces RNA. In cells, RNAP is needed for constructing RNA chains from DNA genes as templates, a process called transcription. RNA polymerase enzymes are essential to life and are found in all organisms and many viruses...
to transcribe the operon.
At least 6 different amino acid operons are known to be regulated by this attenuation.