Functional characterization of the KNOLLE-interacting t-SNARE AtSNAP33 and its role in plant cytokinesis.
Cytokinesis requires membrane fusion during cleavage-furrow ingression in animals and cell plate formation in plants. In Arabidopsis, the Sec1 homologue KEULE (KEU) and the cytokinesis-specific syntaxin KNOLLE (KN) cooperate to promote vesicle fusion in the cell division plane. Here, we characterize AtSNAP33, an Arabidopsis homologue of the t-SNARE SNAP25, that was identified as a KN interactor in a yeast two-hybrid screen. AtSNAP33 is a ubiquitously expressed membrane-associated protein that accumulated at the plasma membrane and during cell division colocalized with KN at the forming cell plate. A T-DNA insertion in the AtSNAP33 gene caused loss of AtSNAP33 function, resulting in a lethal dwarf phenotype. atsnap33 plantlets gradually developed large necrotic lesions on cotyledons and rosette leaves, resembling pathogen-induced cellular responses, and eventually died before flowering. In addition, mutant seedlings displayed cytokinetic defects, and atsnap33 in combination with the cytokinesis mutant keu was embryo lethal. Analysis of the Arabidopsis genome revealed two further SNAP25-like proteins that also interacted with KN in the yeast two-hybrid assay. Our results suggest that AtSNAP33, the first SNAP25 homologue characterized in plants, is involved in diverse membrane fusion processes, including cell plate formation, and that AtSNAP33 function in cytokinesis may be replaced partially by other SNAP25 homologues.
Heese
M
M
Zentrum für Molekularbiologie der Pflanzen, Universität Tübingen, D-72076 Tübingen, Germany.
Gansel
X
X
Sticher
L
L
Wick
P
P
Grebe
M
M
Granier
F
F
Jurgens
G
G
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000033:anatomy & histology / Q000166:cytology* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology*; D018797:Cell Cycle Proteins; D002455:Cell Division; D007425:Intracellular Membranes / Q000737:chemistry; D008561:Membrane Fusion; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000502:physiology; D010641:Phenotype; D010940:Plant Proteins; D050765:Qa-SNARE Proteins; D050766:Qb-SNARE Proteins; D050767:Qc-SNARE Proteins; D017386:Sequence Homology, Amino Acid; D050825:Synaptosomal-Associated Protein 25; D014018:Tissue Distribution; D020798:Two-Hybrid System Techniques; D033921:Vesicular Transport Proteins
C426230:AT1G12360 protein, Arabidopsis; D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; C097724:KNOLLE protein, Arabidopsis; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D010940:Plant Proteins; D050765:Qa-SNARE Proteins; D050766:Qb-SNARE Proteins; D050767:Qc-SNARE Proteins; C439366:SNAP33 protein, Arabidopsis; D050825:Synaptosomal-Associated Protein 25; D033921:Vesicular Transport Proteins