Heterologous expression of syntaxin 6 in Saccharomyces cerevisiae.
The molecular mechanisms of vesicular protein transport in eukaryotic cells are highly conserved. Members of the syntaxin family play a pivotal role in the membrane fusion process. We have expressed rat syntaxin 6 and its cytoplasmic domain in wild-type and pep12 mutant strains of Saccharomyces cerevisiae to elucidate the role of the syntaxin 6-dependent vesicular trafficking step in yeast. Immunofluorescence microscopy revealed a punctate, Golgi-like staining pattern for syntaxin 6, which only partially overlapped with Pep12p in wild-type yeast cells. In contrast to Pep12p, syntaxin 6 was not mislocalized to the vacuole upon expression from 2 micron vectors, which might be attributed to conserved sorting and retention signals. Syntaxin 6 was not capable of complementing the sorting and maturation defects of the vacuolar hydrolase CPY in pep12 null mutants. No dominant negative effects of either syntaxin 6 or syntaxin 6 delta C overexpression on CPY sorting and maturation were observed in wild-type yeast cells. We conclude that syntaxin 6 and Pep12p do not act at the same vesicular trafficking step(s) in yeast and higher eukaryotes.
Götte
Martin
M
Protogenia Research Laboratory, Protogeneia, Inc., D-48149 Münster, Germany. protogenia@technologiehof-ms.de
Stadtbäumer
Andrea
A
D000818:Animals; D015153:Blotting, Western; D002268:Carboxypeptidases / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005057:Eukaryotic Cells / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D006056:Golgi Apparatus / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D021381:Protein Transport / Q000235:genetics; D050765:Qa-SNARE Proteins; D011817:Rabbits; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins
D005656:Fungal Proteins; D008565:Membrane Proteins; C081224:PEP12 protein, S cerevisiae; D050765:Qa-SNARE Proteins; D029701:Saccharomyces cerevisiae Proteins; D002268:Carboxypeptidases