The yeast galactose genetic switch is mediated by the formation of a Gal4p-Gal80p-Gal3p complex.
Saccharomyces cerevisiae responds to galactose as the sole source of carbon by activating the GAL genes encoding the enzymes of the Leloir pathway. Here, we show in vitro that the switch from repressed to activated gene expression involves the interplay of three proteins [an activator (Gal4p), a repressor (Gal80p) and an inducer (Gal3p)] and two small molecules (galactose and ATP). We also show that the galactose- and ATP-dependent interaction between Gal3p and Gal80p occurs without disruption of the Gal80p-Gal4p interaction. Thus, Gal3p-mediated activation of transcription occurs via the formation of a tripartite protein complex.
School of Biological Sciences, The University of Manchester, 2.205 Stopford Building, Oxford Road, Manchester M13 9PT, UK.
A
A
Platt
R J
RJ
Reece
D000255:Adenosine Triphosphate / Q000378:metabolism; D004271:DNA, Fungal / Q000378:metabolism; D004268:DNA-Binding Proteins; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D005686:Galactokinase / Q000235:genetics / Q000378:metabolism; D005690:Galactose / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal / Q000502:physiology; D012331:RNA, Fungal / Q000096:biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation / Q000502:physiology*
D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C052130:GAL4 protein, S cerevisiae; C099289:Gal3 protein, S cerevisiae; D012331:RNA, Fungal; D012333:RNA, Messenger; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D000255:Adenosine Triphosphate; D005686:Galactokinase; D005690:Galactose