Abstract
The Saccharomyces cerevisiae MOT3 gene encodes a nuclear protein implicated in both repression and activation of transcription. However, a mot3 Delta mutation causes only mild phenotypes under normal growth conditions. To learn more about Mot3 function, we have performed a synthetic lethal screen. This screen identified PAN1, a gene required for normal endocytosis, and VPS41, a gene required for vacuolar fusion and protein targeting, suggesting a role for Mot3 in the regulation of membrane-related genes. Transcriptional analyses show that Mot3 represses transcription of ERG2, ERG6 and ERG9, genes required for ergosterol biosynthesis, during both aerobic and hypoxic growth. Chromatin immunoprecipitation experiments suggest that this repression is direct. Ergosterol has been shown to be required for endocytosis and homotypic vacuole fusion, providing a link between Mot3 and these processes. Consistent with these results, mot3 Delta mutants have a number of related defects, including impaired homotypic vacuole fusion and increased sterol levels. Taken together, our data suggest that proper transcriptional regulation of ergosterol biosynthetic genes by Mot3 is important for normal vacuolar function and probably for the endocytic membrane transport system.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Aerobiosis
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Anaerobiosis
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Carrier Proteins / genetics
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Carrier Proteins / physiology
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DNA, Fungal / genetics
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DNA, Fungal / metabolism
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Endocytosis / genetics
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Ergosterol / biosynthesis*
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Fungal Proteins / genetics
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Fungal Proteins / physiology
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Gene Expression Regulation, Fungal
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Genes, Lethal
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Methyltransferases / biosynthesis
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Methyltransferases / genetics
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Microfilament Proteins
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Nuclear Proteins*
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Promoter Regions, Genetic
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RNA, Fungal / biosynthesis
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RNA, Fungal / genetics
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RNA, Messenger / biosynthesis
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RNA, Messenger / genetics
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RNA-Binding Proteins / genetics
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RNA-Binding Proteins / physiology
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Recombinant Fusion Proteins / physiology
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Repressor Proteins / genetics
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Repressor Proteins / physiology*
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / physiology*
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Saccharomyces cerevisiae / ultrastructure
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Saccharomyces cerevisiae Proteins / biosynthesis
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Saccharomyces cerevisiae Proteins / genetics
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Saccharomyces cerevisiae Proteins / physiology*
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Steroid Isomerases / biosynthesis
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Steroid Isomerases / genetics
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Trans-Activators / biosynthesis
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Trans-Activators / genetics
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Trans-Activators / physiology
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Transcription Factors / genetics
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Transcription Factors / physiology*
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Vacuoles / physiology*
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Vacuoles / ultrastructure
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Vesicular Transport Proteins*
Substances
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Carrier Proteins
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DNA, Fungal
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ECM22 protein, S cerevisiae
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Fungal Proteins
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MOT3 protein, S cerevisiae
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Microfilament Proteins
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NPL3 protein, S cerevisiae
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Nuclear Proteins
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PAN1 protein, S cerevisiae
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RNA, Fungal
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RNA, Messenger
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RNA-Binding Proteins
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Recombinant Fusion Proteins
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Repressor Proteins
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Saccharomyces cerevisiae Proteins
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Trans-Activators
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Transcription Factors
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UPC2 protein, S cerevisiae
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VPS41 protein, S cerevisiae
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Vesicular Transport Proteins
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Methyltransferases
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delta 24-sterol methyltransferase
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Steroid Isomerases
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delta(8)-delta(7)-sterol isomerase
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Ergosterol