University of Michigan Medical School
A Photosynthetic Organism’s Toolbox for Adapting to Environmental Conditions
My research program seeks to explain how photosynthetic organisms survive in nearly every habitat on Earth as they inspire the design of artificial light-harvesting systems and are attractive for their use in bio-industrial applications, including hydrogen production, and “greener” ways to produce commodity chemicals and bio-fuels. Our goal is to understand how evolution has fine-tuned photosynthetic organisms to adapt their lifestyles and metabolism to environmental niches that vary broadly with respect to the availability of light and molecular oxygen (O2). We focus on these environmental conditions because both light and O2 profoundly affect the growth and survival of photosynthetic organisms, and are recognized as major hurdles in realizing the potential of these organisms in industrial processes. Towards our goal, my laboratory uses a combination of X-ray crystallography, enzymology, spectroscopy, and metalloprotein expertise to explore each of the following.
- How enzymes build and custom-tune pigments to absorb available light.
- Strategies that photosynthetic organisms use to protect themselves from ultraviolet radiation.
- Mechanisms of enzymes that catalyze equivalent reactions in the presence and absence of O2.
- The molecular basis of how O2, light, and/or redox potential are used as a proxy of environmental conditions.
As photosynthetic microorganisms are regarded as ancient and ubiquitous, and as they straddle the line that divides an anaerobic world from an aerobic one and use sunlight in different habitats as energy, they display versatility that is attractive for industrial applications. Through these studies, we will reveal missing mechanistic details about how photosynthetic organisms perform biosynthetic processes under variable amounts of light and O2. In particular, we will provide a detailed picture of the chemical reactions involved in custom building light-absorbing pigments, reveal the basis of O2 sensitivity in metalloenzymes, establish the connection between environmental signals and flux through biosynthetic pathways, and uncover ways to overcome inefficiencies in employing photosynthetic organisms for various applications.