Harris 9513489 Cytokinesis is a fundamental cellular process subject to both spatial and temporal controls. Specifically, a plane of cell division must be specified and the components necessary for cytokinesis recruited to the incipient division site. Furthermore, cytokinesis must be temporally co-ordinated with nuclear division. Progress towards understanding the molecular mechanisms underlying cytokinesis has been hampered by the lack of a complete inventory of the components required for the process. The overall goal of our research is to help rectify this problem by exploiting the genetically tractable filamentous fungus Aspergillus nidulans to identify and characterize proteins required for cytokinesis. Two such gene products, sepA and sepB, were identified as a result of previous genetic screens. Molecular characterization of the genes encoding these proteins has provided valuable clues about their functional role in cytokinesis. In particular, the sepB gene product appears to serve as an upstream component of a regulatory system which maintains the co-ordination of septum formation and nuclear division, whereas the sepA gene product may be a component of a cortically localized complex of proteins which directs actin polymerization at the division site. Our research will address these hypotheses by using a variety of approaches to determine the sub-cellular location of the sepA and sepB gene products. In addition, genetic screens will be used to enhance our understanding of sepA and sepB function by identifying the proteins with which they interact. A better understanding of the basic mechanisms controlling cell division will be achieved as a result of this research. Furthermore, filamentous fungi have a pronounced impact upon human affairs. Thus, learning how fungal cells grow and divide should have numerous practical benefits. For example, it will provide information which can be used to combat fungal infection of plants, animals, and humans. In addition, it will allow fu ngi to be utilized more efficiently for the production of important food and industrial compounds.
