title: Two eukaryote-specific regions of Hsp82 are dispensable for its viability and signal transduction functions in yeast.
abstract: The 90-kDa heat shock protein (Hsp90) is a molecular chaperone that is very abundant even at normal temperature. It is highly conserved and essential for viability in yeast. To delineate functional domains of Hsp90, we have performed a deletion analysis of one of the two Hsp90 isoforms from budding yeast, Hsp82. The Hsp82 derivatives were tested for complementation of a Hsp90-deficient yeast strain and for their ability to function in two signal transduction pathways that depend on Hsp90. Surprisingly, we found that two salient features of Hsp90 sequences from eukaryotes, the N-terminal charged domain and the extremely conserved C-terminal pentapeptide MEEVD, are dispensable for viability as well as for proper regulation of vertebrate steroid receptors and for pheromone signaling. Moreover, we describe, to our knowledge, the first dominant negative mutant of Hsp90; A Hsp82 derivative that lacks amino acids 538-552 fails to complement but has a dominant negative effect on viability of wild-type strains at moderately elevated temperatures. This mutant may become a valuable tool to study Hsp90 functions both in yeast and in mammalian cells.
authors.affiliation: Départment de Biologie Cellulaire, Université de Genève, Switzerland.
authors.forename: J F
authors.initials: JF
authors.lastname: Louvion
authors.forename: R
authors.initials: R
authors.lastname: Warth
authors.forename: D
authors.initials: D
authors.lastname: Picard
mesh_terms: D000595:Amino Acid Sequence; D017124:Conserved Sequence; D004958:Estradiol / Q000494:pharmacology; D005656:Fungal Proteins / Q000378:metabolism; D018841:HSP90 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D016297:Mutagenesis, Site-Directed; D016133:Polymerase Chain Reaction; D011374:Progesterone / Q000494:pharmacology; D011960:Receptors, Estrogen / Q000096:biosynthesis / Q000187:drug effects; D011980:Receptors, Progesterone / Q000096:biosynthesis / Q000187:drug effects; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins; D017384:Sequence Deletion; D015398:Signal Transduction; D001616:beta-Galactosidase / Q000096:biosynthesis
chemical_list: D005656:Fungal Proteins; C074510:HSP82 protein, S cerevisiae; D018841:HSP90 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D011374:Progesterone; D004958:Estradiol; D001616:beta-Galactosidase