Effects of Bni5 Binding on Septin Filament Organization.
Septins are a protein family found in all eukaryotes (except higher plants) that have roles in membrane remodeling and formation of diffusion barriers and as a scaffold to recruit other proteins. In budding yeast, proper execution of cytokinesis and cell division requires the formation of a collar of circumferential filaments at the bud neck. These filaments are assembled from apolar septin hetero-octamers. Currently, little is known about the mechanisms that control the arrangement and dynamics of septin structures. In this study, we utilized both Förster resonance energy transfer and electron microscopy to analyze the biophysical properties of the septin-binding protein Bni5 and how its association with septin filaments affects their organization. We found that the interaction of Bni5 with the terminal subunit (Cdc11) at the junctions between adjacent hetero-octamers in paired filaments is highly cooperative. Both the C-terminal end of Bni5 and the C-terminal extension of Cdc11 make important contributions to their interaction. Moreover, this binding may stabilize the dimerization of Bni5, which, in turn, forms cross-filament braces that significantly narrow, and impose much more uniform spacing on, the gap between paired filaments.
['Booth|Elizabeth A|EA|', 'Sterling|Sarah M|SM|', 'Dovala|Dustin|D|', 'Nogales|Eva|E|', 'Thorner|Jeremy|J|']
D031541:Fluorescence Resonance Energy Transfer D008854:Microscopy, Electron D008954:Models, Biological D008956:Models, Chemical D008958:Models, Molecular D011485:Protein Binding D025941:Protein Interaction Mapping D055503:Protein Multimerization D012441:Saccharomyces cerevisiae D029701:Saccharomyces cerevisiae Proteins D058112:Septins
electron microscopy FRET analysis analytical ultracentrifugation field-flow fractionation yeast (Saccharomyces cerevisiae)