Molecular and structural biology of phycocyanobilin:ferredoxin oxidoreductases

University Of California-Davis, Davis CA

Investigators

Abstract

Intellectual merit: Phytobilins are pigments that perform significant light harvesting roles in oxygenic photosynthetic organisms from unicellular algae to green plants. When attached to proteins (biliproteins), phytobilins harvest light energy to drive photosynthesis in blue-green, red and brown algae, and trigger adaptive signaling pathways vital to survival in a constantly fluctuating light environment. This project focuses on ferredoxin-dependent bilin reductases (FDBRs), a family of metal-free radical enzymes that are responsible for the synthesis of phytobilin pigment precursors of both classes of light sensor proteins. Using a variety of biochemical and biophysical techniques, this research seeks to elucidate FDBR function at the molecular level via a combination of x-ray crystallography, molecular biology and biochemical analysis. Such knowledge is needed for development of activators/inhibitors of FDBRs that can be used to enhance light perception, growth and development of oxygen-evolving photosynthetic organisms upon which all life on earth depends. These studies also seek to understand the biological role of a unique FDBR gene in the green alga Chlamydomonas reinhardtii, an oxygenic photosynthetic organism that lacks all known light sensing biliproteins. Using genetic, genomic and phenotypic analyses of this organism, several hypotheses for the function of this gene will be assessed. It is anticipated that such studies will lead to insight into new functions of bilin metabolism hitherto unrecognized. Since Chlamydomonas retains features common to plants and animals, this research is expected not only to yield new avenues to improve crop productivity, but could reveal novel bilin-dependent regulatory pathways of relevance to human/animal physiology and disease. The broader impact of this research project will integrate research and education by training scientists at all levels (postdocs, graduate, undergraduate and high school students) in the methods of molecular biology, enzymology, protein chemistry, structural biology, computational biology and reverse genetics. Undergraduates (including an underrepresented minority student) will conduct a number of aspects of this research. Additionally, to broaden participation of underrepresented groups and pto romote teaching, the labs participate in a number of development and minority-training programs, including: MURPPS (Minority Undergraduate Research Participation in the Physical Sciences), SURPRISE (Summer Undergraduate Research Program In Science and Engineering), BUSP (Biology Undergraduate Scholars Program), and in high school programs including Young Scholar Program, SEED (Success in Engineering through Excellence and Diversity Program), and Davis high school advanced biotechnology class. This project is being supported by the Biomolecular Systems cluster in MCB and the Inorganic, Bioinorganic, and Organometallic Chemistry program in CHE.