GENERAL INTEREST

Cellular growth does not occur continuously during the cell cycle and at all points of the cell surface. Morphogenesis is the result of a genetic program coordinated with the cell cycle and exogenous signals and depends on other cellular processes such as intracellular transport, cytoskeleton organisation and cell wall biosynthesis. All those processes must be spatially and temporally controlled to ensure a perfect coordination between morphogenesis and cell cycle progression.

Yeasts are perfect organisms to study morphogenesis, since they are unicellular organisms, the cells are highly polarized, and at the same time they can be easily genetically manipulated. These organisms contain a cell wall, an extracellular structure that completely surrounds the cells and not only serves as protection against adverse environmental conditions, but also determines cell shape. The cell wall can be considered as an exoskeleton of the cell, and it is very complex from the biochemical point of view, containing carbohydrates (?-glucan, ß-glucan, chitin) and mannoproteins. In spite of the rigidity, it is a dynamic structure that is constantly being remodelled to adapt to the morphologic changes of the life cycle and also to the different environmental conditions with the aid of several signal transduction cascades. Assembly of the different components in a three dimensional structure or its modification is a complex, poorly understood, process that involves the participation on different enzymatic activities (i.e., glucan synthases, chitin synthases, transglycosidases) and that needs to be coordinated with cell growth and cell cycle. In addition, the fungal cell wall is widely recognized as an ideal antifungal target, since it is essential for viability and it is absent in animal cells.

The objective of one set of sublines is to analyze different aspects of cellular morphogenesis related to cell wall synthesis, using different yeast and fungi as model systems. The main focus is on the synthases, hydrolases and glycosyltransferases involved in the process. The work aims to understand basic aspects of fungal cell wall synthesis and its coordination with cell growth (polarity, citokynesis and cell separation). Eventually, the results obtained could lead to the identification of new essential fungal proteins that could be used in the search for new antifungal compounds.

The objective of the second set of sublines is to study the regulation of growth polarity and the biosynthesis of fungal cell wall. In particular, the line is focused on the role of Rho GTPases and their regulation (GEFs and GAPs) in these two processes. We aim to understand when and where are the Rho GTPases activated and how the relevant signal transduction pathway is mediated to generate growth polarity.

Sublines from Unit I are integrated in a functional group nominated as a "group of excellence" by the Regional Government (2005-2010 period).