In vitro reactivation of the cytokinetic contractile ring of fission yeast cells.

Cytokinesis is a process by which a mother cell is divided into two daughter cells after chromosome segregation. In both animal and fungal cells, cytokinesis is carried out by the constriction of the contractile ring made up of actin, myosin-II, and other conserved proteins. Detailed genetic and cell biological analysis of cytokinesis has led to the identification of various genes involved in the process of cytokinesis including the cytological description of the process. However, detailed biochemical analysis of the process is lacking. Critical questions that aim to understand aspects, such as the organization of actin and myosin in the contractile ring, the architecture of the ring, and the molecular process of ring contraction, remain unanswered. We have developed a method to address these aspects of cytokinesis. Using the fission yeast Schizosaccharomyces pombe, we present a method whereby cell-ghosts containing functional contractile rings can be isolated and used to perform various biochemical analysis as well as detailed electron microscopy studies.