title: Subcellular localization and trafficking of phytolongins (non-SNARE longins) in the plant secretory pathway.
abstract: SNARE proteins are central elements of the machinery involved in membrane fusion of eukaryotic cells. In animals and plants, SNAREs have diversified to sustain a variety of specific functions. In animals, R-SNARE proteins called brevins have diversified; in contrast, in plants, the R-SNARE proteins named longins have diversified. Recently, a new subfamily of four longins named 'phytolongins' (Phyl) was discovered. One intriguing aspect of Phyl proteins is the lack of the typical SNARE motif, which is replaced by another domain termed the 'Phyl domain'. Phytolongins have a rather ubiquitous tissue expression in Arabidopsis but still await intracellular characterization. In this study, we found that the four phytolongins are distributed along the secretory pathway. While Phyl2.1 and Phyl2.2 are strictly located at the endoplasmic reticulum network, Phyl1.2 associates with the Golgi bodies, and Phyl1.1 locates mainly at the plasma membrane and partially in the Golgi bodies and post-Golgi compartments. Our results show that export of Phyl1.1 from the endoplasmic reticulum depends on the GTPase Sar1, the Sar1 guanine nucleotide exchange factor Sec12, and the SNAREs Sec22 and Memb11. In addition, we have identified the Y48F49 motif as being critical for the exit of Phyl1.1 from the endoplasmic reticulum. Our results provide the first characterization of the subcellular localization of the phytolongins, and we discuss their potential role in regulating the secretory pathway.
authors.affiliation: Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK Faculty of Clinical and Applied Sciences, School of Biomedical Sciences, Leeds Beckett University, Portland Building 611, Leeds Beckett University City Campus, LS1 3HE, Leeds, UK.
authors.forename: Carine
authors.initials: C
authors.lastname: de Marcos Lousa
authors.affiliation: CNRS-University of Bordeaux, UMR 5200 Membrane Biogenesis Laboratory, INRA Bordeaux Aquitaine, 71 Avenue Edouard Bourlaux, CS 20032, 33140 Villenave d'Ornon, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Soubeyrand
authors.affiliation: Molecular Biology and Bioinformatics Unit, Department of Biology, University of Padova, Viale G. Colombo 3, 35131 Padova, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Bolognese
authors.affiliation: CNRS-University of Bordeaux, UMR 5200 Membrane Biogenesis Laboratory, INRA Bordeaux Aquitaine, 71 Avenue Edouard Bourlaux, CS 20032, 33140 Villenave d'Ornon, France.
authors.forename: Valerie
authors.initials: V
authors.lastname: Wattelet-Boyer
authors.affiliation: CNRS-University of Bordeaux, UMR 5200 Membrane Biogenesis Laboratory, INRA Bordeaux Aquitaine, 71 Avenue Edouard Bourlaux, CS 20032, 33140 Villenave d'Ornon, France.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Bouyssou
authors.affiliation: CNRS-University of Bordeaux, UMR 5200 Membrane Biogenesis Laboratory, INRA Bordeaux Aquitaine, 71 Avenue Edouard Bourlaux, CS 20032, 33140 Villenave d'Ornon, France.
authors.forename: Claireline
authors.initials: C
authors.lastname: Marais
authors.affiliation: CNRS-University of Bordeaux, UMR 5200 Membrane Biogenesis Laboratory, INRA Bordeaux Aquitaine, 71 Avenue Edouard Bourlaux, CS 20032, 33140 Villenave d'Ornon, France.
authors.forename: Yohann
authors.initials: Y
authors.lastname: Boutté
authors.affiliation: Molecular Biology and Bioinformatics Unit, Department of Biology, University of Padova, Viale G. Colombo 3, 35131 Padova, Italy patrick.moreau@u-bordeaux.fr francesco.filippini@unipd.it.
authors.forename: Francesco
authors.initials: F
authors.lastname: Filippini
authors.affiliation: CNRS-University of Bordeaux, UMR 5200 Membrane Biogenesis Laboratory, INRA Bordeaux Aquitaine, 71 Avenue Edouard Bourlaux, CS 20032, 33140 Villenave d'Ornon, France Bordeaux Imaging Center, UMS 3420 CNRS, US004 INSERM, University of Bordeaux, 33000 Bordeaux, France patrick.moreau@u-bordeaux.fr francesco.filippini@unipd.it.
authors.forename: Patrick
authors.initials: P
authors.lastname: Moreau
keywords: ER export YF motif; longin domain; phytolongins; protein targeting; secretory pathway; subcellular localization.