title: Dictyostelium discoideum Hsp32 is a resident nucleolar heat-shock protein.
abstract: Hsp32 is a small shock protein in Dictyostelium discoideum that is expressed in growing cells in the absence of heat shock. Here we show that Hsp32 is an Ag-NOR-staining protein capable of binding DNA with high affinity. Hsp32 is also shown to be a resident nucleolar protein both under normal growth conditions and during heat stress. In unstressed cells, Hsp32 localizes to the nucleolar periphery in a pattern reminiscent of the rDNA in this organism. During the first several hours of heat shock, the peripheral localization of Hsp32 is not altered, although rDNA transcription is arrested. Prolonged heat shock causes a condensation of the rDNA. Under these conditions, Hsp32 is no longer predominantly associated with the rDNA, but is instead distributed over the entire nucleolus. Hsp32 therefore retains ist nucleolar localization under prolonged heat shock conditions by associating with nucleolar components other than the rDNA or rRNA.
authors.affiliation: Cellular and Molecular Biology Graduate Training Program, St. Louis University School of Medicine, 1402 South Grand Boulevard, St. Louis, MO 63104, USA.
authors.forename: A M
authors.initials: AM
authors.lastname: Moerman
authors.forename: C
authors.initials: C
authors.lastname: Klein
mesh_terms: D000818:Animals; D002466:Cell Nucleolus / Q000737:chemistry*; D004268:DNA-Binding Proteins / Q000378:metabolism; D004023:Dictyostelium / Q000737:chemistry* / Q000166:cytology / Q000378:metabolism; D005656:Fungal Proteins / Q000032:analysis / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000032:analysis* / Q000378:metabolism*; D006358:Hot Temperature / Q000009:adverse effects; D009687:Nuclear Proteins / Q000737:chemistry; D009697:Nucleolus Organizer Region / Q000737:chemistry / Q000378:metabolism; D000090243:Nucleophosmin; D010750:Phosphoproteins / Q000737:chemistry; D011485:Protein Binding; D015800:Protozoan Proteins; D016601:RNA-Binding Proteins / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D016622:Silver Staining; D000097796:Nucleolin
chemical_list: D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D006360:Heat-Shock Proteins; D009687:Nuclear Proteins; D000090243:Nucleophosmin; D010750:Phosphoproteins; D015800:Protozoan Proteins; D016601:RNA-Binding Proteins; D000097796:Nucleolin; C107554:Hsp32 protein, Dictyostelium discoideum