How would transcription of the E.coli trp operon be affected by the following manipulations of the leader region of trp mRNA?
(a) Increasing the distance (number of bases) between the leader peptide gene and sequence 2.
(b) Increasing the distance between sequences 2 and 3.
(c) Removing sequence 4.
(d) Eliminating the ribosome-binding site for the gene that encodes the leader peptide.
(e) Changing several nucleotides in sequence 3 so that it can base-pair with sequence 4 but not with sequence 2.
How would transcription of the E.coli trp operon be affected by the following manipulations of the leader region of trp mRNA?
(a) Increasing the distance (number of bases) between the leader peptide gene and sequence 2.
(b) Increasing the distance between sequences 2 and 3.
(c) Removing sequence 4.
(d) Eliminating the ribosome-binding site for the gene that encodes the leader peptide.
(e) Changing several nucleotides in sequence 3 so that it can base-pair with sequence 4 but not with sequence 2.
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Complete the Chart.
| Effect on Attentuation | Explanation | |
| Increasing the distance (number of bases) between the leader peptide gene and sequence 2. | ||
| Increasing the distance between sequences 2 and 3. | ||
| Removing sequence 4. | ||
| Changing the two trp codons in the leader pepetide gene to his codons | ||
| Eliminating the ribosome-binding site for the gene that enocodes the leader peptide. | ||
| Changing several nucleotides in sequence 3 so that it can base pair with sequence 4 but not with sequence 2. |
Options:
1) Attenuated by Trp
2) not attenuated by Trp
3) The translating ribosome is too far away to prevent 2:3 hairpin formation
4) The 2:3 hairpin stem and loop is less likely to form, allowing the 3:4 attenuator to form.
5) Sequence 4 is required for attenuator formation
6) Histidine levels now regulate production of Trp gene products.
7) The ribosome is not bound to the sensor site, so attenuation cannot occur.
8) Only the 3:4 attenuator stem and loop can form.
Match the following:
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