Document Detail

Fus1p interacts with components of the Hog1p mitogen-activated protein kinase and Cdc42p morphogenesis signaling pathways to control cell fusion during yeast mating.
MedLine Citation:
PMID:  15020407     Owner:  NLM     Status:  MEDLINE    
Cell fusion in the budding yeast Saccharomyces cerevisiae is a temporally and spatially regulated process that involves degradation of the septum, which is composed of cell wall material, and occurs between conjugating cells within a prezygote, followed by plasma membrane fusion. The plasma membrane protein Fus1p is known to be required for septum degradation during cell fusion, yet its role at the molecular level is not understood. We identified Sho1p, an osmosensor for the HOG MAPK pathway, as a binding partner for Fus1 in a two-hybrid screen. The Sho1p-Fus1p interaction occurs directly and is mediated through the Sho1p-SH3 domain and a proline-rich peptide ligand on the Fus1p COOH-terminal cytoplasmic region. The cell fusion defect associated with fus1Delta mutants is suppressed by a sho1Delta deletion allele, suggesting that Fus1p negatively regulates Sho1p signaling to ensure efficient cell fusion. A two-hybrid matrix containing fusion proteins and pheromone response pathway signaling molecules reveals that Fus1p may participate in a complex network of interactions. In particular, the Fus1p cytoplasmic domain interacts with Chs5p, a protein required for secretion of specialized Chs3p-containing vesicles during bud development, and chs5Delta mutants were defective in cell surface localization of Fus1p. The Fus1p cytoplasmic domain also interacts with the activated GTP-bound form of Cdc42p and the Fus1p-SH3 domain interacts with Bni1p, a yeast formin that participates in cell fusion and controls the assembly of actin cables to polarize secretion in response to Cdc42p signaling. Taken together, our results suggest that Fus1p acts as a scaffold for the assembly of a cell surface complex involved in polarized secretion of septum-degrading enzymes and inhibition of HOG pathway signaling to promote cell fusion.
Bryce Nelson; Ainslie B Parsons; Marie Evangelista; Karen Schaefer; Kathy Kennedy; Steven Ritchie; Tracey L Petryshen; Charles Boone
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Genetics     Volume:  166     ISSN:  0016-6731     ISO Abbreviation:  Genetics     Publication Date:  2004 Jan 
Date Detail:
Created Date:  2004-03-15     Completed Date:  2004-10-26     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  0374636     Medline TA:  Genetics     Country:  United States    
Other Details:
Languages:  eng     Pagination:  67-77     Citation Subset:  IM    
Department of Biology, Queen's University, Kingston, Ontario K7L 3N6, Canada.
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MeSH Terms
Fungal Proteins / metabolism*
Genes, Fungal
MAP Kinase Signaling System
Membrane Fusion
Membrane Proteins / chemistry,  metabolism
Mitogen-Activated Protein Kinases / metabolism*
Models, Biological
Saccharomyces cerevisiae / genetics*,  metabolism*
Saccharomyces cerevisiae Proteins / chemistry,  metabolism*
Two-Hybrid System Techniques
cdc42 GTP-Binding Protein, Saccharomyces cerevisiae / metabolism*
src Homology Domains
Reg. No./Substance:
0/FUS1 protein, S cerevisiae; 0/Fungal Proteins; 0/Membrane Proteins; 0/SHO1 protein, S cerevisiae; 0/Saccharomyces cerevisiae Proteins; EC 2.7.10.-/HOG1 protein, S cerevisiae; EC Protein Kinases; EC GTP-Binding Protein, Saccharomyces cerevisiae

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