I'm reading a patent where they (in S. cerevisae YNP5 strain):

downregulate the ERG9 gene by replacing the native ERG9 promoter with the regulable MET3 promoter

What's a regulable promoter and how does one regulate it? Must one add something to the broth to down-regulate the expression?

I don't see anything special in the culture medium.

  • $\begingroup$ I believe MET3 is repressed by methionine. The repression procedure (amount, concentration, delivery method, etc.) varies depending on the experiment. $\endgroup$
    – CDB
    Commented Apr 26, 2016 at 19:08

1 Answer 1


Regulatable promoter means that the expression of the gene downstream of this promoter can be either induced or repressed. Met3 is an example of such regulatable promoters and it is regulated by the addition of methionine to the media. In yeast, Met3 gene encodes for ATP sulphurylase, an enzyme in the methionine biosynthetic pathway. Upon the addition of methionine, the gene driven by Met3 promoter is repressed, as its expression level is reversely correlated with the concentration of methionine added to the media (Figure from this paper):

enter image description here

  • 1
    $\begingroup$ It would be great if you can also briefly explain what the other "non-inducible" i.e. constitutive promoter is. That will clarify the difference. $\endgroup$
    Commented Apr 27, 2016 at 8:16

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .