Abstract:In eukaryotic cells,most of membrane fusion processes are mediated by SNARE proteins. However,its functional and regulatory mechanisms have not been fully understood. Previous study have shown that yeast sporulation was an ideal model system to manipulate and investigate vesicle fusion machinery including SNARE proteins. The t-SNARE protein Sso1 involved in this process is an orthologue of syntaxin 1A which is required for the synaptic vesicle fusion,both share 51% homology at the SNRE domains. However,although their functional and amino acid sequence are similar,Sso1/syntaxin 1A chimera cannot complement the sporulation deficiency of sso1?驻 mutant when SNARE domain of Sso1 is replaced completely by syntaxin 1A. To determine which residues are critical for Sso1 function,chimera and mutational analyses are further conducted. The results showed that the SSO1/syntaxin 1A chimera gain the functionality by replacing Ala220 residue to Glu in the syntaxin 1A SNARE domain. By contrast,Sso1 lose its function by mutating the corresponding amino acid residue,Glu218 into Ala. Thus,Glu218 residue is specifically required for Sso1 function.
