ABSTRACT
Modulating composition and shape of biological membranes is an emerging mode of regulation of cellular processes. We investigated the global effects that such perturbations have on a model eukaryotic cell. Phospholipases A(2) (PLA(2)s), enzymes that cleave one fatty acid molecule from membrane phospholipids, exert their biological activities through affecting both membrane composition and shape. We have conducted a genome-wide analysis of cellular effects of a PLA(2) in the yeast Saccharomyces cerevisiae as a model system. We demonstrate functional genetic and biochemical interactions between PLA(2) activity and the Rim101 signaling pathway in S. cerevisiae. Our results suggest that the composition and/or the shape of the endosomal membrane affect the Rim101 pathway. We describe a genetically and functionally related network, consisting of components of the Rim101 pathway and the prefoldin, retromer and SWR1 complexes, and predict its functional relation to PLA(2) activity in a model eukaryotic cell. This study provides a list of the players involved in the global response to changes in membrane composition and shape in a model eukaryotic cell, and further studies are needed to understand the precise molecular mechanisms connecting them.
Subject(s)
Cell Membrane/chemistry , Cell Shape/genetics , Epistasis, Genetic , Phospholipases A2/genetics , Repressor Proteins/genetics , Saccharomyces cerevisiae Proteins/genetics , Saccharomyces cerevisiae , Cell Membrane/genetics , Cell Membrane/physiology , Cell Proliferation , Epistasis, Genetic/physiology , Gene Regulatory Networks/physiology , Genetic Linkage , Hydrogen-Ion Concentration , Models, Biological , Molecular Chaperones/genetics , Molecular Chaperones/metabolism , Molecular Chaperones/physiology , Multiprotein Complexes/genetics , Multiprotein Complexes/metabolism , Multiprotein Complexes/physiology , Organisms, Genetically Modified , Saccharomyces cerevisiae/cytology , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/growth & development , Saccharomyces cerevisiae/ultrastructure , Signal Transduction/genetics , Signal Transduction/physiologyABSTRACT
Cytoplasmic mRNA localization provides a means of generating cell asymmetry and segregating protein activity. Previous studies have identified two mRNAs that localize to the bud tips of the yeast Saccharomyces cerevisiae. To identify additional localized mRNAs, we immunoprecipitated the RNA transport components She2p, She3p, and Myo4p and performed DNA microarray analysis of their associated RNAs. A secondary screen, using a GFP-tagged RNA reporter assay, identified 22 mRNAs that are localized to bud tips. These messages encode a wide variety of proteins, including several involved in stress responses and cell wall maintenance. Many of these proteins are asymmetrically localized to buds. However, asymmetric localization also occurs in the absence of RNA transport, suggesting the existence of redundant protein localization mechanisms. In contrast to findings in metazoans, the untranslated regions are dispensable for mRNA localization in yeast. This study reveals an unanticipated widespread use of RNA transport in budding yeast.
