A systemic analysis of cell wall protein networks in the cell walls of green organisms

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Plant cell walls provide the largest biomass on earth and have been utilized for human consumption. Given the current need for renewable energy and hydrocarbon sources, research has been focused on how to facilitate conversion of this biomass into biofuels. The long-term goal of this study is to deepen our knowledge of plant cell wall physiology during growth and development, thereby guiding efforts to harness plant biomass productivity.The major plant cell wall proteins are hydroxyproline-rich glycoproteins (HRGPs) that share many features with animal collagens. Molecular genetics studies indicate that HRGPs play essential roles during plant cell wall assembly and remodeling; however, their individual roles have been largely unexplored as they are embedded in complex polysaccharides in plant cell walls. Therefore, I sought an alternative system to study the HRGP functions. A green algal model system Chlamydomonas, offers a great opportunity to probe the details of HRGPs relevant to plant cell walls, since it possesses HRGP families homologous to the plant HRGPs, and its cell walls consist mostly of HRGPs but little or no polysaccharides, which allows microscopic and biochemical techniques to analyze molecular features of HRGPs.Main objective of my research program is to understand biological functions of HRGPs in constructing cell walls. To achieve the objective, I will systemically examine HRGP families between green algae and plants, and uncover common HRGPs that would play fundamental roles in green organisms. Secondly, I will build a comprehensive library of the mutants defective in cell wall functions of Chlamydomonas. Their phenotypes and encoded products will collectively elucidate how green organisms evolve a system that controls biosynthesis and assembly of HRGPs in order to build dynamic but strong extracellular macromolecular networks.