Defining glucan dikinase phosphorylation of starch from multiple kingdoms

University Of Florida, Gainesville FL

Investigators

Abstract

Starch plays a central role in human food, agricultural animals feed, biofuels, and as an industrial feedstock. Starch from cereal crops and tubers account for 50-80% of daily caloric intake. In the U.S., 36% of corn is dedicated to animal feed and 34% is converted into biofuels. Starch is both a first-generation biofuel and a feedstock for molecular hydrogen and oil production by micro-algae. It is also an industrial feedstock for paper, textiles, adhesives, and plastics. Therefore, defining the pathways that control starch metabolism is needed in order to develop novel strategies that manipulate these pathways and satisfy the growing starch demand. This project will define molecular energy storage mechanisms from algae to plants while teaching students to test hypotheses using bioinformatics, biophysics, structural biology, cell biology, and enzymology. The broader impacts of this project may increase participation of women and underrepresented minorities in STEM, improve STEM education and educator development, help develop a diverse and globally competitive STEM workforce, and increase public scientific literacy and engagement with science technology. Reversible phosphorylation of starch glucose is the only known natural modification of starch, and it directly influences starch hydration, crystallinity, freeze-thaw stability, viscosity, and transparency, which are all central to industrial applications. Starch producing organisms possess either one or two glucan dikinases that phosphorylate starch glucose. Their activity is critical for the production and utilization of starch in vivo. Despite their key biological role, little is known regarding the physical and functional basis for glucan dikinase action. To define the biology and biochemistry of glucan dikinases, the researchers focus on green plants which possess two glucan dikinases. Further, there is currently no means to harness their unique activity. This research will develop methods to utilize glucan dikinases by focusing on algal systems that possess only one glucan dikinase. The project combines state-of-the-art biophysical approaches with biochemistry, cell biology, algal genetics, and glucan analysis to define the function, dynamics, structures, and regulation of glucan dikinases. The objectives of this research are to: (I) define the molecular enzymology of glucan dikinases, (II) determine structural dynamics and crystal structures of glucan dikinases, and (III) elucidate the biological function of algal glucan phosphorylation. This award was co-funded by the Division of Molecular and Cellular Biosciences, the Division of Integrative Organismal Systems, and the Rules of Life Venture Fund. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.