Minisymposium 21: Protein and Vesicle Trafficking

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Abs # M2103: Protein transport to the lytic vacuole is based both on transient contacts between Golgi and mobile prevacuoles and on the maturation of prevacuolar compartments

Presenter:	Paris, Nadine       Contact Presenter
Authors	Brandizzi, Federica  (D)   Saint-Jean, Bruno  (A)   Hawes, Chris  (B)   Neuhaus, Jean-Marc  (C)   Paris, Nadine  (A)
Affiliations:	(A): UMR-CNRS 6037 IFRMP23, Universite de Rouen, France (B): Research School of Biological & Molecular Sciences, Oxford Brookes University, United Kingdom (C): Laboratoire de Biologie Moleculaire et Cellulaire, Universite de Neuchatel, Switzerland (D): Department of Biology, University of Saskatchewan, Saskatoon, Canada

Prevacuolar compartments (PVCs) are secretory organelles that receive cargo from the Golgi apparatus and subsequently deliver it to the lytic vacuole. A characterization of the dynamics of these organelles has yet to emerge in plant cells. To contribute to our knowledge of PVCs in vivo, we generated fluorescent fusion proteins, XFP-PS1, with the transmembrane and the cytosolic regions of pea BP-80, a vacuolar sorting receptor (VSR) for proteins of the lytic vacuole. Here we show by live confocal imaging that the labeled PVC is a post-Golgi BFA-resistant organelle distinct from lytic and storage vacuolar membranes and that it associates transiently with intermediate compartments containing aleurain-GFP, a cargo transported to the lytic vacuole via pea BP-80. The labeled PVC is highly mobile and moves independently to the Golgi. However, PVC and Golgi dock at times to form a short-lived hetero-duplex that appears tethered by transient tubule-like extensions. PVCs are also constantly rearranged since they are capable of fission and homotypic fusion with other PVCs. These rearrangements are wortmannin-sensitive and are necessary for segregating the receptor and its cargo into separate organelles.