Transcriptional rewiring of fungal galactose-metabolism circuitry.
BACKGROUND
The Leloir-pathway genes encode the enzymatic machinery involved in the metabolism of galactose.


RESULTS
In the distantly related fungi Saccharomyces cerevisiae and Candida albicans, the genes encoding these enzymes are syntenically arranged, but the upstream regulatory regions are highly divergent. In S. cerevisiae, the Leloir-pathway genes are positively regulated by Gal4p acting through the UAS(G) sequence CGG(N(11))CCG. However, in C. albicans, the Gal4p and UAS(G) combination is found to regulate genes unrelated to galactose metabolism. We identified a palindromic sequence that acts to control GAL10 expression in C. albicans in the presence of galactose. This palindrome is found upstream of other Leloir-pathway genes in C. albicans, and in the absence of other regulatory sequences, activation of expression through this sequence in the presence of galactose requires Cph1p, the homolog of the Ste12p transcription factor of S. cerevisiae.


CONCLUSIONS
Although the cellular process of galactose induction of the Leloir pathway is conserved between the two organisms, the regulatory circuits achieving the cellular process are completely distinct.
Martchenko
Mikhail
M
Department of Biology, McGill University, Montreal, Quebec H3A 1B1, Canada.
Levitin
Anastasia
A
Hogues
Herve
H
Nantel
Andre
A
Whiteway
Malcolm
M
D000595:Amino Acid Sequence; D001483:Base Sequence; D002176:Candida albicans / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D005690:Galactose / Q000378:metabolism*; D020869:Gene Expression Profiling; D015966:Gene Expression Regulation, Fungal; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D011401:Promoter Regions, Genetic; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
C090837:CPH1 protein, Candida albicans; D005656:Fungal Proteins; C518355:GAL10 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D005690:Galactose