ABSTRACT
The Swc4p protein, encoded by an essential gene, is shared by two chromatin-remodeling complexes in Saccharomyces cerevisiae cells: NuA4 (nucleosome acetyltransferase of H4) and SWR1. The SWR1 complex catalyzes ATP-dependent exchange of the nucleosomal histone H2A for H2AZ (Htz1p). The activity of NuA4 is responsible mainly for the acetylation of the H4 histone but also for the acetylation of H2A and H2AZ. In this work we investigated the role of the Swc4p protein. Using random mutagenesis we isolated a collection of swc4 mutants and showed that the essential function of Swc4p resides in its N-terminal part, within the first 269 amino acids of the 476-amino acid-long protein. We also demonstrated that Swc4p is able to accommodate numerous mutations without losing its functionality under standard growth conditions. However, when swc4 mutants were exposed to methyl methanesulfonate (MMS), hydroxyurea or benomyl, severe growth deficiencies appeared, pointing to an involvement of Swc4p in many chromatin-based processes. The mutants' phenotypes did not result from an impairment of histone acetylation, as in the mutant which bears the shortest isolated variant of truncated Swc4p, the level of overall H4 acetylation was unchanged.
Subject(s)
Saccharomyces cerevisiae Proteins/chemistry , Saccharomyces cerevisiae Proteins/metabolism , Saccharomyces cerevisiae/metabolism , Acetylation , Alleles , Amino Acid Sequence , Base Sequence , Chromatin Assembly and Disassembly , DNA Primers/genetics , DNA, Fungal/genetics , Genes, Fungal , Histone Acetyltransferases , Histones/chemistry , Molecular Sequence Data , Mutagenesis , Peptide Fragments/chemistry , Peptide Fragments/genetics , Peptide Fragments/metabolism , Phenotype , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae Proteins/genetics , Sequence Deletion , Sequence Homology, Amino AcidABSTRACT
Genes encoding peroxisomal proteins in the yeast Saccharomyces cereviasiae are induced in the presence of oleate in growth medium. This induction is known to be mediated by the binding of a heterodimer of transcription factors Oaf1 and Pip2 to an upstream activating sequence called ORE (oleate response element). By analyzing expression of nine ORE-containing genes we show that the presence of an ORE sequence is not sufficient to confer oleate inducibility, as three such genes were in fact expressed constitutively. Moreover, some of the oleate-inducible genes undergo activation even in the absence of Pip2. Using coimmunoprecipitation we show that, when Pip2 is missing, Oaf1 may form homodimers which apparently substitute for the Oaf1-Pip2 heterodimer.
Subject(s)
DNA-Binding Proteins/metabolism , Gene Expression Regulation, Fungal , Oleic Acid/metabolism , Peroxisomes/genetics , Saccharomyces cerevisiae Proteins/metabolism , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/metabolism , Transcription Factors/metabolism , Dimerization , Gene Expression/drug effects , Immunoprecipitation , Oleic Acid/pharmacology , Response Elements , Saccharomyces cerevisiae/drug effects , Saccharomyces cerevisiae Proteins/genetics , Transcription Factors/geneticsABSTRACT
The Saccharomyces cerevisiae HSP31 (YDR533c) gene encodes a protein that belongs to the DJ-1/PfpI family and its function is unknown. Homologs to Hsp31p polypeptide can be found in organisms from all systematic groups of eukaryotes and prokaryotes, and the functions of the vast majority of them are also hypothetical. One of the homologs is human protein DJ-1. Various amino acid substitutions within this protein correlate with early onset hereditary Parkinson's disease. The deletion of the HSP31 gene displays no apparent phenotype under standard growth conditions, but a thorough functional analysis of S. cerevisiae revealed that its absence makes the cells sensitive to a subset of reactive oxygen species (ROS) generators. HSP31 is induced under conditions of oxidative stress in a YAP1-dependent manner. Similar to other stress response genes, it is also induced in the postdiauxic phase of growth and this induction is YAP1-independent. The patterns of sensitivities to various ROS generators of the hsp31Delta strain and the strain with the deletion of SOD1, another gene defending the cell against ROS, are different. We postulate that Hsp31p protects the cell against oxidative stress and complements other stress protection systems within the cell.
Subject(s)
Heat-Shock Proteins/physiology , Molecular Chaperones/physiology , Reactive Oxygen Species/metabolism , Saccharomyces cerevisiae Proteins/physiology , Saccharomyces cerevisiae/physiology , Cell Survival , DNA Primers , Genotype , Heat-Shock Proteins/genetics , Molecular Chaperones/genetics , Plasmids , Polymerase Chain Reaction , Restriction Mapping , Saccharomyces cerevisiae/drug effects , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/growth & development , Saccharomyces cerevisiae Proteins/geneticsABSTRACT
The Saccharomyces cerevisiae spindle pole body (SPB) consists of numerous proteins forming the outer, inner and central plaques. The protein Cnm67 is an important component of the outer plaque. The C-terminus of this protein contains a determinant important for its SPB localization. We identified a protein encoded by YOR129c which interacts with this C-terminus in the two-hybrid system. YOR129c and CNM67 exhibit weak genetic interaction. The double deletion strain yor129cdelta cnm67delta exhibits moderately increased resistance to 0.1M LiCl and hygromycin B compared with the cnm67delta single mutant. We propose that the YOR129c protein is an accessory factor associated with the cytoplasmic face of SPB and plays a role in cation homeostasis and/or multidrug resistance.
