Abstract
The cell plate is formed by the fusion of Golgi apparatus-derived vesicles in the center of the phragmoplast during cytokinesis in plant cells. A dynamin-like protein, phragmoplastin, has been isolated and shown to be associated with cell plate formation in soybean by using immunocytochemistry. In this article, we demonstrate that similar to dynamin, phragmoplastin polymerizes to form oligomers. We fused soybean phragmoplastin with the green fluorescence protein (GFP) and introduced it into tobacco BY-2 cells to monitor the dynamics of early events in cell plate formation. We demonstrate that the chimeric protein is functional and targeted to the cell plate during cytokinesis in transgenic cells. GFP-phragmoplastin was found to appear first in the center of the forming cell plate, and as the cell plate grew outward, it redistributed to the growing margins of the cell plate. The redistribution of phragmoplastin may require microtubule reorganization because the microtubule-stabilizing drug taxol inhibited phragmoplastin redistribution. Our data show that throughout the entire process of cytokinesis, phragmoplastin is concentrated in the area in which membrane fusion is active, suggesting that phragmoplastin participates in an early membrane fusion event during cell plate formation. Based on the dynamics of GFP-phragmoplastin, it appears that the process of cell plate formation is completed in two phases. The first phase is confined to the cylinder of the phragmoplast proper and is followed by a second phase that deposits phragmoplast vesicles in a concentric fashion, resulting in a ring of fluorescence, with the concentration of vesicles being higher at the periphery. In addition, overexpression of GFP-phragmoplastin appears to act as a dominant negative, slowing down the completion of cell plate formation, and often results in an oblique cell plate. The latter appears to uncouple cell elongation from the plane of cell division, forming twisted and elongated cells with longitudinal cell divisions.
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Selected References
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- Asada T., Shibaoka H. Isolation of polypeptides with microtubule-translocating activity from phragmoplasts of tobacco BY-2 cells. J Cell Sci. 1994 Aug;107(Pt 8):2249–2257. doi: 10.1242/jcs.107.8.2249. [DOI] [PubMed] [Google Scholar]
- Chen M. S., Obar R. A., Schroeder C. C., Austin T. W., Poodry C. A., Wadsworth S. C., Vallee R. B. Multiple forms of dynamin are encoded by shibire, a Drosophila gene involved in endocytosis. Nature. 1991 Jun 13;351(6327):583–586. doi: 10.1038/351583a0. [DOI] [PubMed] [Google Scholar]
- Dombrowski J. E., Raikhel N. V. Isolation of a cDNA encoding a novel GTP-binding protein of Arabidopsis thaliana. Plant Mol Biol. 1995 Sep;28(6):1121–1126. doi: 10.1007/BF00032672. [DOI] [PubMed] [Google Scholar]
- Hinshaw J. E., Schmid S. L. Dynamin self-assembles into rings suggesting a mechanism for coated vesicle budding. Nature. 1995 Mar 9;374(6518):190–192. doi: 10.1038/374190a0. [DOI] [PubMed] [Google Scholar]
- Lukowitz W., Mayer U., Jürgens G. Cytokinesis in the Arabidopsis embryo involves the syntaxin-related KNOLLE gene product. Cell. 1996 Jan 12;84(1):61–71. doi: 10.1016/s0092-8674(00)80993-9. [DOI] [PubMed] [Google Scholar]
- Miao G. H., Hong Z., Verma D. P. Two functional soybean genes encoding p34cdc2 protein kinases are regulated by different plant developmental pathways. Proc Natl Acad Sci U S A. 1993 Feb 1;90(3):943–947. doi: 10.1073/pnas.90.3.943. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Nakayama M., Yazaki K., Kusano A., Nagata K., Hanai N., Ishihama A. Structure of mouse Mx1 protein. Molecular assembly and GTP-dependent conformational change. J Biol Chem. 1993 Jul 15;268(20):15033–15038. [PubMed] [Google Scholar]
- Rothman J. H., Raymond C. K., Gilbert T., O'Hara P. J., Stevens T. H. A putative GTP binding protein homologous to interferon-inducible Mx proteins performs an essential function in yeast protein sorting. Cell. 1990 Jun 15;61(6):1063–1074. doi: 10.1016/0092-8674(90)90070-u. [DOI] [PubMed] [Google Scholar]
- Samuels A. L., Giddings T. H., Jr, Staehelin L. A. Cytokinesis in tobacco BY-2 and root tip cells: a new model of cell plate formation in higher plants. J Cell Biol. 1995 Sep;130(6):1345–1357. doi: 10.1083/jcb.130.6.1345. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Smith L. G., Hake S., Sylvester A. W. The tangled-1 mutation alters cell division orientations throughout maize leaf development without altering leaf shape. Development. 1996 Feb;122(2):481–489. doi: 10.1242/dev.122.2.481. [DOI] [PubMed] [Google Scholar]
- Takei K., McPherson P. S., Schmid S. L., De Camilli P. Tubular membrane invaginations coated by dynamin rings are induced by GTP-gamma S in nerve terminals. Nature. 1995 Mar 9;374(6518):186–190. doi: 10.1038/374186a0. [DOI] [PubMed] [Google Scholar]
- Takei K., Mundigl O., Daniell L., De Camilli P. The synaptic vesicle cycle: a single vesicle budding step involving clathrin and dynamin. J Cell Biol. 1996 Jun;133(6):1237–1250. doi: 10.1083/jcb.133.6.1237. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Thomas C., DeVries P., Hardin J., White J. Four-dimensional imaging: computer visualization of 3D movements in living specimens. Science. 1996 Aug 2;273(5275):603–607. doi: 10.1126/science.273.5275.603. [DOI] [PubMed] [Google Scholar]
- van der Bliek A. M., Redelmeier T. E., Damke H., Tisdale E. J., Meyerowitz E. M., Schmid S. L. Mutations in human dynamin block an intermediate stage in coated vesicle formation. J Cell Biol. 1993 Aug;122(3):553–563. doi: 10.1083/jcb.122.3.553. [DOI] [PMC free article] [PubMed] [Google Scholar]