Research

Our research program is primarily concerned with elucidating the mechanism of the energy-storing reactions in photosynthetic organisms, as well as understanding the origin and early evolution of photosynthesis.

The chemical reactions leading to long-term energy storage in photosynthetic systems take place within the membrane-bound reaction center complex and an associated group of proteins that make up an electron transport chain. One of the central goals of our research is to identify the molecular parameters responsible for the fact that essentially every photon absorbed by the system leads to stable products. To this end, we do a variety of kinetic, thermodynamic and structural measurements on antenna complexes, reaction centers, electron transport proteins and isolated pigments, using a number of techniques, including ultrafast laser flash photolysis and UV-VIS, fluorescence and electron spin resonance spectroscopies, as well as biochemical and molecular biological analysis.

Structural comparisons of reaction center proteins.

The appearance of photosynthesis and other metabolic processes such as nitrogen fixation had profound effects on the evolution of advanced life on Earth. Our analysis of whole bacterial genomes has revealed that these metabolic processes have complex evolutionary histories, including substantial horizontal gene transfer. We have also used a combination of genomic, molecular evolution techniques and biochemical analysis to identify and characterize previously unknown enzyme complexes with novel activities.

Electron microscopic tomogram of a dividing photosynthetic bacterium

Selected Publications

• Sattley WM, Madigan MT, Swingley WD, Cheung PC, Clocksin KM, Conrad AL, Dejesa LC, Honchak BM, Jung DO, Karbach LE, Kurdoglu A, Lahiri S, Mastrian SD, Page LE, Taylor HL, Wang ZT, Raymond J, Chen M, Blankenship RE and Touchman JW (2008) The Genome of Heliobacterium modesticaldum, a Phototrophic Representative of the Firmicutes Containing the Simplest Photosynthetic Apparatus. J. Bacteriology In Press.
• Read EL, Schlau-Cohen G, Engel GS, Wen J, Blankenship RE, Fleming GR (2008) Visualization of Excitonic Structure in the Fenna-Matthews-Olson Photosynthetic Complex by Polarization-Dependent Two-Dimensional Electronic Spectroscopy. Biophysical Journal In Press doi:10.1529/biophysj.107.128199.
• "Niche adaptation and genome expansion in the chlorophyll d-producing cyanobacterium Acaryochloris marina." Swingley WD, Chen M, Cheung PC, Conrad AL, Dejesa LC, Hao J, Honchak BM, Karbach LE, Kurdoglu A, Lahiri S, Mastrian SD, Miyashita H, Page LE, Ramakrishna P, Satoh S, Sattley WM, Shimada Y, Taylor HL, Tomo T, Tsuchiya T, Wang ZT, Raymond J, Mimuro M, Blankenship RE and Touchman JW Proc. Nat’l. Acad. Sci. USA 105: 2005-2010 (2008)
• "Using automated Markov clustering to reconstruct the cyanobacterial species tree from conserved protein families." Swingley WD, Blankenship RE and Raymond J Molecular Biology and Evolution 25: 1-12 (2008)
• "The origin of the oxygen-evolving complex." Raymond J and Blankenship RE Coordination Chemistry Reviews 252: 377-383 (2008)
• "The Expression and Association of Group IV Nitrogenase NifD And NifH Homologs in the Non-Nitrogen Fixing Archaeon Methanocaldococcus jannaschii." Staples CR, Lahiri S, Raymond J, Von Herbulis L, Mukhophadhyay B and Blankenship RE J.Bacteriology 189: 7392-7398.(2007)
• "Femtosecond spectroscopy of the primary charge separation in reaction centers of Chloroflexus aurantiacus with selective excitation in Qy and Soret bands." Xin Y, Lin S and Blankenship RE J. Phys. Chem. A 111: 9367-9373 (2007)
• "Cross-Peak Specific Two Dimensional Electronic Spectroscopy." Read EL, Engel GS, Calhoun TR, Mancal T, Ahn TK, Blankenship RE, and Fleming GR Proc. Nat’l. Acad. Sci. USA, 104: 14203-14208 (2007)
• "Evidence for wavelike energy transfer through quantum coherence in photosynthetic systems." Engel GS, Calhoun TR, Read EL, Ahn TK, Mancal T, Cheng Y-C, Blankenship RE and Fleming GR Nature, 446: 782-786 (2007)
• "Spectral Signatures of Photosynthesis. I. Review of Earth Organisms." Kiang N, Siefert J, Govindjee, Blankenship RE, Astrobiology 7: 222-251 (2007)
• "Spectral signatures of photosynthesis. II. Coevolution with other stars and the atmosphere on extrasolar worlds." Kiang N, Segura A, Tinetti G, Govindjee, Blankenship RE, Cohen M, Siefert J, Crisp D and Meadows VS Astrobiology 7: 252-274 (2007)
• "Pigment Analysis of Chlorothrix halophila, a Filamentous Anoxygenic Phototrophic Bacterium by High Pressure Liquid Chromatography and Mass Spectrometry." Olson TL, van de Meene AML and Blankenship RE J. Bacteriology 189: 4187-4195 (2007)
• "Characterization of the Photosynthetic Apparatus of Chlorothrix halophila: A Filamentous, Anaerobic Photoautotroph." van de Meene AML, Olson TL and Blankenship RE J. Bacteriology 189: 4196-4203 (2007)
• "Variable fluorescence in green sulfur bacteria." Hohmann-Marriott, M. and Blankenship RE Biochim. Biophys. Acta 1767: 106-113 (2007)
• "A ubiquitous marine phototroph with a novel carbon-fixation pathway." Swingley WD, Gholba S, Mastrian SD, Matthies HJ, Hao J, Ramos H, Acharya CR, Conrad AL, Taylor HL, Dejesa LC, Shah MK, O’Huallachain ME, Lince MT, Blankenship RE, Beatty JT and Touchman JW J. Bacteriology, 189: 683-690 (2007)