The Vid vesicle to vacuole trafficking event requires components of the SNARE membrane fusion machinery

C. Randell Brown, Jingjing Liu, Guo Chiuan Hung, Donald Carter, Dongying Cui, Hui Ling Chiang

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Abstract

The key gluconeogenic enzyme fructose-1,6-bisphosphatase (FBPase) is targeted to Vid vesicles when glucose-starved cells are replenished with glucose. Vid vesicles then deliver FBPase to the vacuole for degradation. A modified alkaline phosphatase assay was developed to study the trafficking of Vid vesicles to the vacuole. For this assay, FBPase was fused with a truncated form of alkaline phosphatase. Under in vivo conditions, FBPase-Δ60Pho8p was targeted to the vacuole via Vid vesicles, and it exhibited Pep4p- and Vid24p-dependent alkaline phosphatase activation. Vid vesicle-vacuole targeting was reconstituted using Vid vesicles that contained FBPase-Δ60Pho8p. These vesicles were incubated with vacuoles in the presence of cytosol and an ATP-regenerating system. Under in vitro conditions, alkaline phosphatase was also activated in a Pep4p- and Vid24p-dependent manner. The GTPase Ypt7p was identified as an essential component in Vid vesicle-vacuole trafficking. Likewise, a number of v-SNAREs (Ykt6p, Nyv1p, Vti1p) and homotypic fusion vacuole protein sorting complex family members (Vps39p and Vps41p) were required for the proper function of Vid vesicles. In contrast, the T-SNARE Vam3p was a necessary vacuolar component. Vid vesicle-vacuole trafficking exhibits characteristics similar to heterotypic membrane fusion events.

Original languageEnglish (US)
Pages (from-to)25688-25699
Number of pages12
JournalJournal of Biological Chemistry
Volume278
Issue number28
DOIs
StatePublished - Jul 11 2003

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All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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