EAGER: Understanding the design principles of biological light harvesting

Arizona State University, Scottsdale AZ

Investigators

Abstract

Photosynthesis is the most powerful biological process on earth. The first step in photosynthesis is the capture of energy in the form of light by biological antenna. Currently, the ability to design and construct functional biological antenna is severely limited. This project will significantly advance the knowledge of how light energy is captured and converted by biological antenna during photosynthesis. The products of photosynthesis, oxygen and organic matter, are used to make and power virtually all other life forms on earth in addition to providing a significant portion of humanity’s energy needs. Because light is a diffuse energy source, plants and other photosynthetic microorganisms deploy large arrays of light harvesting antenna in their cells to concentrate light into specific locations where chemical reactions occur at high rates. These biological antennae are made from hundreds of light absorbing molecules held together in ways which ensures operation with near perfect efficiency. This proposal will identify the critical structural elements in antennae and explore ways to engineer them in cells. Understanding the design principles of biological light harvesting and developing methods to construct new antennae will open new ways to improve light harvesting systems in crops and increase their productivity. The project will support the career of one female post-doctoral fellow and one graduate student. In addition, a program aimed at introducing children into the basic concepts of Science, technology, engineering, art and mathematics (STEAM) will be developed with local schools. Biological antennae are mostly membrane bound and contain hundreds of light harvesting pigments. The ability to construct functional antenna variants in cells is limited and this hinders the understanding of antenna in their natural context, as they form super complexes with photochemical reaction centers. This proposal focuses on one of the major antennae systems on the planet called IsiA, which is prevalent in the cyanobacteria phylum. Due to the large diversity of cyanobacteria, a large number of IsiA sequence variants evolved and can be retrieved from public databases. This proposal will explore the functional significance of this variability by introducing chimeric antennae into a model cyanobacterium. In response to stress IsiA is induced and forms very large and symmetrical antennae assemblies in cells. The abilities of chimeric antennae to from these assemblies, to carry out energy transfer and to support cellular growth under stress will be measured. The results will identify the mechanisms by which antennae contribute to cellular resistance to stress and will generate a cellular platform for the construction of novel antennae systems with desired properties. 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.