Abstract
Summary: Glucans are important components of the cell wall and acts to maintain the cell shape. It was confirmed that the secreted glucans of fission yeast stretch into fibrils and then pack into bundles, which are oriented in parallel and connected in a side-by-side manner to develop wide ribbon-like structures. It is suggested that the wide glucan fibrils function to maintain the cell wall integrity by forming the network structures. The analysis of mutants of glucan synthase indicated that theβ-1, 3-andα-1, 3-glucans are essential for the formation of cell-wall layered structures, and each glucan plays a different role. It is also indicated that theα-glucan possibly acts in packing the glucan network. Onlyβ-1, 3-glucan plays a vital role in the primary septum formation. This finding strongly suggested thatβ-1, 3-glucan synthesis, together with the contraction of the contractile ring, is essential in the progress of the septum formation, and shows that one of theβ-1, 3-glucan synthases, Bgslp, functioned in this process. Studies of the glucan synthase localization indicated that the defect inα-1, 3-glucan synthesis affects the secondary septum formation, therefore theα-glucan synthase, Moklp, located in the septum region from the beginning of the septum formation. It is suggested thatα-1, 3-glucan may have a role in the early stage of the septum formation.
