Abstract
Expression of the barley (Hordeum vulgare) HVA22 gene is induced by environmental stresses, such as dehydration, salinity, and extreme temperatures, and by a plant stress hormone, abscisic acid. Genes sharing high level of sequence similarities with HVA22 exist in diverse eukaryotic organisms, including animals, plants, and fungi, but not in any prokaryotic organisms. The yeast (Saccharomyces cerevisiae) HVA22 homolog, Yop1p, has been shown to interact with the GTPase-interacting protein, Yip1p. Deletion of YOP1 led to only a modest reduction of the stationary phase titer at 37C. A synthetic enhancement mutant screen was performed in the yop1 deletion background to identify genes interacting with YOP1. The open reading frame YOR165W (renamed SEY1 for synthetic enhancement of YOP1) was identified as a YOP1-dependent complementation gene. The yeast SEY1 is a homolog of the Arabidopsis RHD3 gene whose mutations cause the accumulation of transport vesicles near the tips of defective root hairs. The yeast double mutant of yop1 and sey1 is defective in vesicular traffic as evidenced by the accumulation of transport vesicles and the decrease in invertase secretion. Based on these observations, we suggest that Yop1p/HVA22 regulates vesicular traffic in stressed cells either to facilitate membrane turnover, or to decrease unnecessary secretion.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Alleles
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Amino Acid Sequence
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Arabidopsis / genetics
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Arabidopsis Proteins / genetics
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Biological Transport / genetics
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Biological Transport / physiology
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Carrier Proteins / genetics
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Cell Cycle Proteins / genetics
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GTP-Binding Proteins / genetics
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Gene Expression Regulation, Plant
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Heat-Shock Proteins / genetics*
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Hordeum / genetics*
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Humans
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Membrane Transport Proteins / genetics
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Microscopy, Electron
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Molecular Sequence Data
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Mutation
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Plant Proteins / genetics
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Saccharomyces cerevisiae / genetics*
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Saccharomyces cerevisiae / ultrastructure
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Saccharomyces cerevisiae Proteins / genetics*
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Secretory Vesicles / physiology
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Sequence Homology, Amino Acid
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Transcription Factor DP1
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Transcription Factors / genetics
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Two-Hybrid System Techniques
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Vesicular Transport Proteins*
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rab GTP-Binding Proteins / genetics
Substances
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Arabidopsis Proteins
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AtHVA22 protein, Arabidopsis
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Carrier Proteins
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Cell Cycle Proteins
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HVA1 protein, Hordeum vulgare
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Heat-Shock Proteins
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Membrane Transport Proteins
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Plant Proteins
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SEY1 protein, S cerevisiae
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Saccharomyces cerevisiae Proteins
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Transcription Factor DP1
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Transcription Factors
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USO1 protein, S cerevisiae
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Vesicular Transport Proteins
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YOP1 protein, S cerevisiae
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GTP-Binding Proteins
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RHD3 protein, Arabidopsis
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YPT1 protein, S cerevisiae
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rab GTP-Binding Proteins