Molecular Identification of 26 Syntaxin Genes and their Assignment to the Different Trafficking Pathways in Paramecium

• Published in: Traffic (Copenhagen, Denmark) Denmark), 2007-05, Vol.8 (5), p.523-542
• Main Authors: Kissmehl, Roland, Schilde, Christina, Wassmer, Thomas, Danzer, Carsten, Nuehse, Kathrin, Lutter, Kaya, Plattner, Helmut
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Biological Transport - physiology; Cell Membrane - metabolism; Cell Membrane - ultrastructure; Endoplasmic Reticulum - metabolism; Endoplasmic Reticulum - ultrastructure; exocytosis; Golgi; Golgi Apparatus - metabolism; Golgi Apparatus - ultrastructure; Green Fluorescent Proteins - genetics; Green Fluorescent Proteins - metabolism; Intracellular Membranes - metabolism; Intracellular Membranes - ultrastructure; Microscopy, Immunoelectron; Models, Biological; Models, Molecular; Molecular Sequence Data; Paramecium; Paramecium - genetics; Paramecium - physiology; Paramecium - ultrastructure; Phylogeny; Protein Isoforms - chemistry; Protein Isoforms - genetics; Protein Isoforms - physiology; Protein Structure, Tertiary - genetics; Protozoan Proteins - chemistry; Protozoan Proteins - genetics; Protozoan Proteins - physiology; Qa-SNARE Proteins - chemistry; Qa-SNARE Proteins - genetics; Qa-SNARE Proteins - physiology; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; RNA Interference; Sequence Analysis, DNA; Sequence Homology, Amino Acid; SNAREs; syntaxin; Transfection; Transport Vesicles - metabolism; Transport Vesicles - ultrastructure; Vesicular Transport Proteins - chemistry; Vesicular Transport Proteins - genetics; Vesicular Transport Proteins - physiology
• ISSN: 1398-9219; 1600-0854
• DOI: 10.1111/j.1600-0854.2007.00544.x

SNARE proteins have been classified as vesicular (v)‐ and target (t)‐SNAREs and play a central role in the various membrane interactions in eukaryotic cells. Based on the Paramecium genome project, we have identified a multigene family of at least 26 members encoding the t‐SNARE syntaxin (PtSyx) that can be grouped into 15 subfamilies. Paramecium syntaxins match the classical build‐up of syntaxins, being ‘tail‐anchored’ membrane proteins with an N‐terminal cytoplasmic domain and a membrane‐bound single C‐terminal hydrophobic domain. The membrane anchor is preceded by a conserved SNARE domain of ∼60 amino acids that is supposed to participate in SNARE complex assembly. In a phylogenetic analysis, most of the Paramecium syntaxin genes were found to cluster in groups together with those from other organisms in a pathway‐specific manner, allowing an assignment to different compartments in a homology‐dependent way. However, some of them seem to have no counterparts in metazoans. In another approach, we fused one representative member of each of the syntaxin isoforms to green fluorescent protein and assessed the in vivo localization, which was further supported by immunolocalization of some syntaxins. This allowed us to assign syntaxins to all important trafficking pathways in Paramecium.