Heme-Induced Heme-Repressed Regulatory Mechanisms

Question

[pegahtv]

We are reading literature to infer regulatory interactions. We have come to this sentence:

Enhancement of expression of CYC7 in the null strain indicated that the ROX1 factor is required for repression of CYC7 to its normal low level of expression, consistent with evidence that CYC7 has a hybrid heme-induced, heme-repressed regulatory mechanism

It is clear that it says: ROX1 is repressing CYC7. But does anyone knows what does "heme-induced heme-repressed regulatory mechanisms" mean? Does it mean that CYC7 has autoregulation?

Answer 1

[Steve Lianoglou]

1. This isn't really a bioinformatics question, right?
2. A link to the paper would be most helpful (even though I doubt you'll get anybody to read it); but

The following is speculation since I have no context to go on

I'm going to just take a guess -- is the "null strain" a ROX1 knockout?

It sounds like CYC7 is induced by heme, is that right? It also sounds like ROX1 is induced by heme, which (I guess) they show also represses CYC7.

If the above is true, it sounds like they show that the expression of CYC7 is turned on in the presence of heme eg. "CYC7 is heme-induced" (when ROX1 is KO'd). But, the expression of ROX1 is also induced by heme which, in turn, represses CYC7 so CYC7 is also "heme-repressed" ... and there's your hybrid.

[pegahtv]

@Steve Lianoglou Thank you very much for your answer. Actually my field of bioinformatics, and I am reading these papers at part of my theses. The link to the paper is: http://mcb.asm.org/content/8/11/4651.short I don't understand how you inferred that ROX1 is induced by heme. And one more question. When they say null strain, do they mean KO?

[Steve Lianoglou]

Regarding how I inferred the ROX1 relationship, it's because (1) I'm familiar w/ how biologists talk; and (2) I was reading between the lines of what you wrote. As you spend more time in the field talking to more biologists and reading more biological papers (maybe even take some (pure) biology classes) this will be easier for you to do. A "null strain" means that the strain of whatever organism (here, yeast) is missing something. So if they talk about a "ROX1 null strain", they are talking about a strain of yeast that are missing the ROX1 gene.