title: Pun1p is a metal ion-inducible, calcineurin/Crz1p-regulated plasma membrane protein required for cell wall integrity.
abstract: Under conditions of environmental stress, the plasma membrane is involved in several regulatory processes to promote cell survival, like maintenance of signaling pathways, cell wall organization and intracellular ion homeostasis. PUN1 encodes a plasma membrane protein localizing to the ergosterol-rich membrane compartment occupied also by the arginine permease Can1. We found that the PUN1 (YLR414c) gene is transcriptionally induced upon metal ion stress. Northern blot analysis of the transcriptional regulation of PUN1 showed that the calcium dependent transcription factor Crz1p is required for PUN1 induction upon heavy metal stress. Here we report that mutants deleted for PUN1 exhibit increased metal ion sensitivity and morphological abnormalities. Microscopical and ultrastructural observations revealed a severe cell wall defect of pun1∆ mutants. By using chemical cross-linking, Blue native electrophoresis, and co-immunoprecipitation we found that Pun1p forms homo-oligomeric protein complexes. We propose that Pun1p is a stress-regulated factor required for cell wall integrity, thereby expanding the functional significance of lateral plasma membrane compartments.
authors.affiliation: Department of Microbiology, Immunobiology and Genetics, University of Vienna, A-1030 Vienna, Austria.
authors.forename: Dagmar
authors.initials: D
authors.lastname: Hosiner
authors.forename: Gerhard
authors.initials: G
authors.lastname: Sponder
authors.forename: Anton
authors.initials: A
authors.lastname: Graschopf
authors.forename: Siegfried
authors.initials: S
authors.lastname: Reipert
authors.forename: Rudolf J
authors.initials: RJ
authors.lastname: Schweyen
authors.forename: Christoph
authors.initials: C
authors.lastname: Schüller
authors.forename: Markus
authors.initials: M
authors.lastname: Aleschko
mesh_terms: D015152:Blotting, Northern; D019703:Calcineurin / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D015151:Immunoblotting; D007477:Ions / Q000494:pharmacology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D019216:Metals, Heavy / Q000494:pharmacology*; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D009154:Mutation; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: C109868:CRZ1 protein, S cerevisiae; D004268:DNA-Binding Proteins; D007477:Ions; D008565:Membrane Proteins; D019216:Metals, Heavy; C558931:Pun1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D049452:Green Fluorescent Proteins; D019703:Calcineurin