Tryptophan (Trp) Operon: a repressible operon - UGG codons in E. coli & TRAP protein in B. subtilis

What is tryptophan operon? How does trp operon work? What is function of UGG codons in trp operon? What is the function of hairpins and attenuator in trp operon? How does TRAP protein system regulate trp operon in Bacillus subtilis? What is a repressible operon? What is the substrate in the trp operon? How does trpR repressor work? What is the function of the repressor in the trp operon? Find out answers to all these questions in this deep-dive video. Jump to your favorite section:
00:00 Outline
00:20 Lac vs Trp operon
03:36 trpR
04:39 trpEDCBA
06:21 Leader region
09:03 Hairpin formation
11:08 NO tryptophan
12:38 Ribosome at UGG codon
15:06 YES tryptophan
17:22 Attenuation (Termination)
20:14 Terminology
21:30 Trp operon in B. subtilis
25:53 TRAP protein

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[theCrux]

Erratum: I realize that I have been dismissive about the function of TrpR at around 16:00. TrpR binding is not useless. It does manage to stop the movement of RNA polymerase. The binding therefore does matter. The initial block of trpR is an important step to make the cell respond quickly to Trp availability. Think of TrpR as an immediate switch to repression state where as if you didn't have it, the switch would be slower because it takes a while to make the trp-tRNA (so the leader peptide cannot be immediately formed). Overtime, the trpR amount goes down since it represses itself. So, after a while the available trpR is lower, which affects how often the operator can be blocked by the repressor. But when it manages to bind the operator, the RNA polymerase is blocked. If the RNA polymerase is not blocked, a leader peptide is made.

Thanks to one of the commenter for catching this :)

[shanu]

Thank you dear sir.
Sir can u provide notes of your every lecture please that is very helpful for me.🙏

[e.n.]

nice video man, exactly what I need for my exam:) I hope to see more videos like mRNA vaccine one, where you explain more interesting stuffs! However, keep going with your work and don't give up, you are doing amazing things, at least for those who are interested in science and molecular biology:)

[as]

It was helpful and great work, thanks. But i have a confusion about the function of TrpR repressor protein. It seems like it doesn't do anything? am i wrong or?

[manujena]

Please make cell biology and immunology lecture..