A purified Drosophila septin complex forms filaments and exhibits GTPase activity.
Christine M. Field,Omayma Al-Awar,Jody Rosenblatt,Mei Lie Wong,Bruce Alberts,Timothy J. Mitchison +5 more
TL;DR: A model of filament structure is discussed and speculated as to how the filaments are organized within cells and identify the septins as members of the GTPase superfamily.
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Abstract: Septin proteins are necessary for cytokinesis in budding yeast and Drosophila and are thought to be the subunits of the yeast neck filaments. To test whether septins actually form filaments, an immunoaffinity approach was used to isolate a septin complex from Drosophila embryos. The purified complex is comprised of the three previously identified septin polypeptides Pnut, Sep2, and Sep1. Hydrodynamic and sequence data suggest that the complex is composed of a heterotrimer of homodimers. The complex copurifies with one molecule of bound guanine nucleotide per septin polypeptide. It binds and hydrolyzes exogenously added GTP. These observations together with conserved sequence motifs identify the septins as members of the GTPase superfamily. We discuss a model of filament structure and speculate as to how the filaments are organized within cells.
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Citations
Cytokinesis in Drosophila melanogaster
TL;DR: Strong fly genetics combined with single‐cell analysis, live imaging, and biochemical assays will continue to provide important insights into the mechanism of cytokinesis, significantly contributing to current understanding of this important cellular process.
Nucleotide binding and filament assembly of recombinant yeast septin complexes
TL;DR: It is shown here that the nucleotide-binding sites of the septins show drastic changes on formation of higher oligomers, and the binary core Cdc3p-Cdc12p complex does not form filaments, but the ternary and quaternary complexes form bundles of paired filaments.
Borg5/Cdc42EP1 restricts contractility and motility in epithelial MDCK cells
David Cohen,Dawn Fernandez,Francisco Lázaro‐Diéguez,Beatrix M. Uberheide,Anne Müsch +4 more
TL;DR: Borg5/Cdc42EP1 restricts contractility, cell-cell adhesion tension, and motility in epithelial MDCK cells, promoting columnar morphology by limiting septin-dependent stress fibers and myosin activity, and interacting with Myosin-IIA to regulate cell shape and organization.
Borg/septin interactions and the assembly of mammalian septin heterodimers, trimers, and filaments.
Peter J. Sheffield,Carey J. Oliver,Brandon E. Kremer,Sitong Sheng,Zhifeng Shao,Ian G. Macara +5 more
TL;DR: It is shown that stable, soluble septin heterodimers can be produced by co-expression from bicistronic vectors in bacteria and that the co- expression of three septins results in their assembly into filaments.
Septin Organization and Dynamics for Budding Yeast Cytokinesis
Maritzaida Varela Salgado,Simonetta Piatti +1 more
TL;DR: Septins play a crucial role in yeast cytokinesis, forming a dynamic collar at the division site that regulates cytokinetic machinery assembly and activity, ensuring coordinated cell division with chromosome segregation and cell wall deposition.
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