An e coli mutant isolated is simultaneously unable to...

An E. coli mutant isolated is simultaneously unable to utilize a large number of sugars, e.g. lactose, arabinose, maltose, as carbon source. However, genetic analysis shows that each of the operons responsible for metabolism of each sugar is free of mutation. Name a specific gene the mutation of which may account for this outcome? Explain.

Transcript

00:01 So it looks like there is an e.

00:02 Coli mutant isolated that is simultaneously unable to utilize large numbers of sugars as a carbon source, such as lactose, arabinose, and maltose.

00:10 But the genetic analysis showed that each of these operon itself actually has no mutations.

00:16 Name a specific gene, the mutation which may account for this outcome exploit.

00:22 Point.

00:22 So first of all, we know this is not a cis problem, which means that this, i guess i would call this the dna sequence of the operon has no mutation.

00:41 So it's not a sequence issue.

00:55 So from there, you can tell that since it's not because of a dna sequence of operon and it must be a regulatory protein.

01:04 We call this transmutation.

01:09 So this means that it's not the dna region that has issue, but the protein regulated has a problem.

01:19 So this regulatory protein is mutated.

01:23 Now, there are several regulated protein for each of those operon.

01:29 However, however, they must be something in common because there's a large number of sugars such as lactose, arabinose, and maltose that all have issues.

01:41 So this means that it must be a regulatory protein that is involved in all three operon.

01:56 So from there, we can actually tell that it is very likely that the potential mutation mutation lies in this cyclic amp crp regulatory system.

02:11 Or we call this cap protein.

02:14 So this is a possibility because cap protein is such a commonly used regulatory protein involving involving all three pathways.

02:25 So this is the c -cap protein is a short name for the catabolite activator protein.

02:37 So c, then activator protein.

02:56 So this protein actually is a, i would say, they activate a protein bind to an enhancer region right before the promoter region of all these operons so that it will actually cause the polymerase to bind to this region tightly, so which will initiate a strong, i would say, transcription.

03:25 So let me sort of explain each one of those operons.

03:29 So, if you look at the lac operon, there will be a remote repressor lac i...

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