TVP23 interacts genetically with the yeast SNARE VTI1 and functions in retrograde transport from the early endosome to the late Golgi

Ivar S Stein , Anna Gottfried , Jana Zimmermann , Gabriele Fischer von Mollard (1)

1 Fakultät für Chemie [Universität Bielefeld]

SNARE proteins contribute to specific recognition between transport vesicles and target membranes and are required for fusion of membranes. The SNARE Vti1p is required for several transport steps between late Golgi, endosomes and the vacuole in the yeast Saccharomyces cerevisiae. Here we identified the late Golgi membrane protein TVP23 as a multicopy suppressor of the growth defect in vti1-2 cells. By contrast, the growth defect in vti1-11 cells was not suppressed by TVP23 overexpression. Deletion of TVP23 aggravated the growth defect in vti1-2 cells. Genetic interactions between TVP23 and vti1-2 were not found in transport from the late Golgi via the late endosome to the vacuole or in transport from the Golgi directly to the vacuole. These data suggest that Tvp23p is not involved in forward transport from the late Golgi. Therefore retrograde traffic to the late Golgi was analyzed. vti1-2 cells accumulated GFP-Snc1p within the cell indicating that retrograde transport from the early endosome to the late Golgi was defective in these cells. Deletion of TVP23 in vti1-2 cells resulted in a synthetic defect in GFP-Snc1p recycling while tvp23Δ cells had a slight defect. These data indicate that Tvp23p performs a partially redundant function in retrograde transport from the early endosome to the late Golgi. This transport step was unaffected in vti1-11 cells providing an explanation for the allele specific multicopy suppression by TVP23.

Mots clés: Life Sciences

Ivar S Stein, Anna Gottfried, Jana Zimmermann, Gabriele Fischer von Mollard. TVP23 interacts genetically with the yeast SNARE VTI1 and functions in retrograde transport from the early endosome to the late Golgi. Biochemical Journal, 2009, 419 (1), pp.229-236. ⟨10.1042/BJ20081973⟩. ⟨hal-00479102⟩