MOLECULAR-BASIS OF CELL INTEGRITY AND MORPHOGENESIS IN SACCHAROMYCES-CEREVISIAE

In fungi and many other organisms, a thick outer cell wall is responsi ble for determining the shape of the cell and for maintaining its inte grity. The budding yeast Saccharomyces cerevisiae has been a useful mo del organism for the study of cell wall synthesis, and over the past f ew decades, many aspects of the composition, structure, and enzymology of the cell wall have been elucidated. The cell wall of budding yeast s is a complex and dynamic structure; its arrangement alters as the ce ll grows, and its composition changes in response to different environ mental conditions and at different times during the yeast life cycle. In the past few years, we have witnessed a prolific genetic and molecu lar characterization of some key aspects of cell wall polymer synthesi s and hydrolysis in the budding yeast. Furthermore, this organism has been the target of numerous recent studies on the topic of morphogenes is, which have had an enormous impact on ow understanding of the intra cellular events that participate in directed cell wall synthesis. A nu mber of components that direct polarized secretion, including those in volved in assembly and organization of the actin cytoskeleton, secreto ry pathways, and a series of novel signal transduction systems and reg ulatory components have been identified. Analysis of these different c omponents has suggested pathways by which polarized secretion is direc ted and controlled. Our aim is to offer an overall view of the current understanding of cell wall dynamics and of the complex network that c ontrols polarized growth at particular stages of the budding yeast cel l cycle and life cycle.