Mso1p regulates membrane fusion through interactions with the putative N-peptide-binding area in Sec1p domain 1.

Sec1p/Munc18 (SM) family proteins regulate SNARE complex function in membrane fusion through their interactions with syntaxins. In addition to syntaxins, only a few SM protein interacting proteins are known and typically, their binding modes with SM proteins are poorly characterized. We previously identified Mso1p as a Sec1p-binding protein and showed ...
that it is involved in membrane fusion regulation. Here we demonstrate that Mso1p and Sec1p interact at sites of exocytosis and that the Mso1p-Sec1p interaction site depends on a functional Rab GTPase Sec4p and its GEF Sec2p. Random and targeted mutagenesis of Sec1p, followed by analysis of protein interactions, indicates that Mso1p interacts with Sec1p domain 1 and that this interaction is important for membrane fusion. In many SM family proteins, domain 1 binds to a N-terminal peptide of a syntaxin family protein. The Sec1p-interacting syntaxins Sso1p and Sso2p lack the N-terminal peptide. We show that the putative N-peptide binding area in Sec1p domain 1 is important for Mso1p binding, and that Mso1p can interact with Sso1p and Sso2p. Our results suggest that Mso1p mimics N-peptide binding to facilitate membrane fusion.
Mesh Terms:
Amino Acid Substitution, Binding Sites, Membrane Fusion, Membrane Proteins, Models, Molecular, Munc18 Proteins, Mutation, Peptides, Protein Binding, Protein Interaction Mapping, Protein Stability, Protein Structure, Secondary, Protein Structure, Tertiary, Qa-SNARE Proteins, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Spores, Fungal
Mol. Biol. Cell
Date: Apr. 15, 2010
Download Curated Data For This Publication
Switch View:
  • Interactions 13