Yeast is magical. It gives our bread and beer its deliciousness, and provides biologists with a fantastic tool for understanding cell biology. Many of our monumental cell biology discoveries were due to yeast, so please whisper a heartfelt “Thank you” to yeast the next time you enjoy a beer. Today’s image is from a paper describing the structure of the septin network required for cell division in yeast.
Many yeast species divide by budding – a mother cell replicates its genome within its nucleus while a small bud forms and grows. The nucleus divides and the bud splits off of the mother cell. This split between mother and bud, or cytokinesis, depends on structural proteins called septins. Although the structure and function of septins has been studied for years, exactly how they are arranged at the bud neck of dividing yeast was not clear. Despite the small size of the bud neck, Bertin and colleagues recently imaged septin ultrastructure in dividing yeast cells by using improved techniques of electron microscopy that allow better preservation of membranes, combined with three-dimensional reconstruction of images. Specifically, Bertin and colleagues found septin filaments that ran both parallel and perpendicular to the mother-bud axis. In the images above, a view of the bud neck near the top of the membrane (top) shows circumferential filaments (green arrows). In a deeper view of the bud neck (bottom), filaments that follow the contour of the bud neck (next to red lines) can be seen, as well as a cross-sectional view of the circumferential filaments (green arrows).
Bertin, A., McMurray, M., Pierson, J., Thai, L., McDonald, K., Zehr, E., Garcia, G., Peters, P., Thorner, J., & Nogales, E. (2011). Three-dimensional ultrastructure of the septin filament network in Saccharomyces cerevisiae Molecular Biology of the Cell, 23 (3), 423-432 DOI: 10.1091/mbc.E11-10-0850