6.8 years ago by
There are two well known example related to the regulation of galactose metabolism in S.cerevisiae and C.albicans. These cases are well described in the article Martchenko et al, 'Transcriptional rewiring of fungal galactose-metabolism circuitry'. Curr Biol. 2007, and also in Rokas et al Transcriptional Rewiring: The Proof Is in the Eating, Curr. Biol 2007. There is also some description in chapter 3 of the book "The Origins of Evolutionary Innovations" by Andreas Wagner, and in these slides I did for a journal club on the same book.
In S.cerevisiae, GAL4 is involved in the galactose metabolism, regulating the expression of other genes that are able to convert this sugar. In C.albicans, the regulation of the same enzymes is done by other genes (one of which is CPH1), while the homologue of GAL4 is associated to the telomer, and is involved in an unknown function.
At the same time, the homologue of the gene CPH1 which regulates galactose metabolism in C.albicans, is involved in mating in S.cerevisiae.
- GAL4 -> involved in galactose metabolism in S.cerevisiae, involved in an unknown function related to telomeres in C.albicans.
- CPH1 -> involved in galactose metabolism in C.albicans, but involved in mating in S.cerevisiae (where it is known as STE12).
image taken from http://www.sciencedirect.com/science/article/pii/S096098220701562X#gr1
In general, I think that you are looking for homologues that have different function, your best bet is to search among transcription factors. A small mutation in certain positions of the sequence of a transcript factor can have a huge impact on the specificity of the transcription factor, making it recognize a completely different sequence. This leads to a change of function of the transcript factor, while the rest of the sequence remains conserved.