Open AccessESCRT-III Protein Snf7 Mediates High-Level Expression of the SUC2 Gene via the Rim101 Pathway
Author(s) -
Peter Weiß,
Stefanie Huppert,
Ralf Kölling
Publication year - 2008
Publication title -
eukaryotic cell
Language(s) - English
Resource type - Journals
eISSN - 1535-9778
pISSN - 1535-9786
DOI - 10.1128/ec.00194-08
Subject(s) - biology , transcription factor , mutant , saccharomyces cerevisiae , transcription (linguistics) , gene , gene expression , phenotype , dna binding protein , protein fragment complementation assay , derepression , regulation of gene expression , complementation , microbiology and biotechnology , genetics , linguistics , philosophy , psychological repression
The yeast (Saccharomyces cerevisiae ) Snf7 family consists of six highly charged, coiled-coil-forming proteins involved in multivesicular body (MVB) formation. Although all proteins perform a common function at late endosomes, individual mutants also show distinct phenotypes. This suggests that Snf7 homologues have additional functions separate from their role in MVB formation. In this report, we explored the molecular basis for thes ucrose-n onf ermenting phenotype ofsnf7 mutants. Our Northern blotting experiments provide evidence that Snf7 is involved in the regulation ofSUC2 transcription. The Snf7-dependent regulation ofSUC2 transcription does not appear to involve the transcription factor Mig1, since Mig1 phosphorylation after glucose derepression was not affected in a Δsnf7 mutant. Instead, we show that Snf7 influencesSUC2 expression by regulating the level of the transcription factor Nrg1. Snf7 exerts its effects on Nrg1 levels through activation of the transcription factor Rim101, which is part of the yeast alkaline response pathway (“Rim101 pathway”). This is supported by the findings that deletion ofRIM101 or overexpression ofNRG1 from theADH1 promoter leads to the sameSUC2 expression level as deletion ofSNF7 . In addition, deletion of other components of the Rim101 pathway, likeRIM13 andRIM20 , led to the same growth phenotype on raffinose media as deletion ofSNF7 . Furthermore, Snf7 turned out to be dispensable forSUC2 expression in anNRG1 deletion background. Thus, the effects of Snf7 onSUC2 expression can be completely accounted for by its effect on Nrg1 levels.