Georgia Institute of TechnologyCSSB
alt tag for imagealt tag for imagealt tag for image

Dr. Bridgette Barry

Professor

School of Chemisty and Biochemisty

member
Dr. Bridgette Barry

    Contact information:
  • School of Chemisty and Biochemisty
  • 315 Ferst Drive
  • IBB, Room 3232
  • Atlanta, GA 30332, Mail Code: 0400
  • Tel: 404-385-6085
  • Fax: 404-894-2295
  • Email:

Research Interests

Biological Electron Transfer, Membrane Biophysics, Vibrational Spectroscopy, EPR (Electron Paramagnetic Resonance) Spectroscopy, Photosynthesis Oxido-reductase enzymes play central roles in cellular metabolism. For example, membrane-associated redox enzymes carry out photosynthetic and respiratory energy conversion. Work in my laboratory is centered on these enzymes, and, in particular, on the mechanism of energy conversion in plant photosynthesis. In plant photosynthesis, light absorption leads to a long distance electron transfer reaction. We are interested in how proteins control the direction and rate of the electron transfer reactions and in how the electron transfer reactions are coupled with protonation reactions, conformational changes, and other chemical reactions, such as photosynthetic oxygen production. We study the structure and function of photosynthetic reaction centers that have been isolated from plants and cyanobacteria. We are also building simple models of these complex proteins, in order to elucidate fundamental principles. To reach our goals, my laboratory employs a broad combination of techniques, including vibrational spectroscopy, EPR spectroscopy, site-directed mutagenesis, and mass spectrometry. Specific projects are described below.

Post-translational modifications in membrane proteins. Amino acid side chains in proteins can be modified during or after the synthesis of the protein. The modified amino acid may have unique reactivity or may provide a cellular signal. There is little known about such modifications in photosynthetic enzymes. My group is using mass spectrometry, proteomics, and peptide mapping to identify interesting, modified amino acids in a photosynthetic membrane protein, photosystem II. A subset of these modified amino acids is located at the active site for photosynthetic water oxidation and may play a role in the structure and function of the enzyme. Other photosystem II modifications may be important in signaling for the turnover or degradation of the enzyme inside the cell.

Electron transfer in enzymes and in model compounds. Long distance electron transfer in proteins involves step-wise reactions between pairs of redox-active prosthetic groups, which act as catalytic intermediates. These prosthetic groups include covalently and non-covalently bound cofactors, such as hemes, pheophytins, and chlorophyll, as well as amino acid side chains. An important long-term goal of this research project is to determine how electron transfer rates are influenced by changes in the structure and environment of these redox intermediates. We are investigating electron transfer mechanisms that involve redox-active amino acids in enzymes and in model peptides. We are using EPR and time-resolved vibrational spectroscopy, and, in collaborative efforts, electron spin-echo envelope modulation (ESEEM) and density functional (DFT) calculations. We are also investigating electron transfer mechanisms that involve tetrapyrrole-derived cofactors. This work will help to elucidate the factors responsible for midpoint potential control in oxido-reductases.

Oxygen production in plant photosynthesis. Oxygenic photosynthesis is essential in the maintenance of life on earth. This type of photosynthesis requires the concerted action of two reaction centers, which convert light energy into a transmembrane charge separation. One of these reaction centers, photosystem II (PSII), catalyzes the oxidation of water and the production of molecular oxygen. PSII accumulates the four oxidizing equivalents necessary for oxygen production at a manganese-containing catalytic site. PSII consists both of integral, membrane-spanning subunits and of extrinsic subunits, that do not span the membrane. The extrinsic subunit known as the manganese stabilizing protein, MSP, prevents loss of manganese from the PSII active site and is required for optimal rates of oxygen evolution. In this project, vibrational spectroscopy is being used to obtain detailed information about structural changes occurring during oxygen production. The ultimate goal is to determine how oxygen-oxygen bond formation occurs. In addition, vibrational spectroscopy is being employed to test a possible mechanism by which MSP may influence water oxidation. These experiments will provide new information about the function and assembly of complex membrane proteins.

Faculty Page
Research Group

Selected Publications

"Calcium exchange and structural changes during the photosynthetic oxygen evolving cycle," Antonio De Riso, David Jenson, and Bridgette A. Barry, 2006, Biophys. J. 91, In press.
"Time resolved vibrational spectroscopy detects a protein-based intermediate in the photosynthetic oxygen-evolving cycle," Bridgette A. Barry, Ian Cooper, Antonio De Riso, Scott Brewer, Dung Vu, and R. Brian Dyer, 2006, Proc. Nat. Acad. Sci., 103, 7288-7291 (See Commentary in that issue).
"Normal modes of redox active tyrosine: conformational dependence and comparison to experiment," Kevin Range, Idelisa Pujols-Ayala, Darrin York, and Bridgette A. Barry, J. Phys. Chem. B, 2006, 110, 10970-10981.
"Calcium ligation in photosystem II under inhibiting conditions," Bridgette A. Barry, Antonio De Riso, Charles Hicks, and David Jenson, Biophys. J., 2005, 89, 393-401.
"Role for bound water and CH-pi aromatic interactions in photosynthetic electron transfer," C. A. Sacksteder, S. L. Bender, B. A. Barry, J. Am. Chem. Soc., 2005, 127 (21), 7879-7890.
"Redox-active tyrosine residues in pentapeptides," Ilya Vassiliev, Adam Offenbacher, and Bridgette A. Barry, J. Phys. Chem. B, 2005, 109, 23077-23085.
"Redox active tyrosine residues: new insights from model compound studies," Bridgette A. Barry and ?lof Einarsd?tti, J. Phys. Chem. B, 2005, 109, 23077-23085 (Feature article).
"Tyrosyl radicals in Photosystem I," I. Pujols-Ayala and B. A. Barry, Biochim. Biophys. Acta, 2004,1655C, 205-216.
"Evidence for a post-translational modification, aspartyl aldehyde, in a photosynthetic membrane protein," L. B. Anderson, A. J. A. Ouellette, J. Eaton-Rye, M. Maderia, M. J. MacCoss, J. R. Yates III, and B. A. Barry, J. Amer. Chem. Soc., 2004, 126, 8399-8405.
"Structural studies of the manganese-stabilizing subunit of Photosystem II," B. Svensson, D. M. Tiede, D. R. Nelson, and B. A. Barry, Biophys. J., 2004, 86, 1807-1812.
"Specific isotope labeling and photooxidation-linked structural changes in the manganese stabilizing subunit of Photosystem II," R. Sachs, K. M. Halverson, and B.A. Barry, J. Biol. Chem., 2003, 278, 44222-44229.
"Evidence for spontaneous structural changes in a dark-adapted state of Photosystem II," K. M. Halverson and B. A. Barry, Biophys. J., 2003, 85, 2581-2588.
"Redox-active tyrosine residues: Role for the peptide bond in electron transfer," I. Pujols-Ayala, C. A. Sacksteder, and B. A. Barry, J. Am. Chem. Soc. Commun., 2003, 125, 7536-7538.
"Sucrose and glycerol effects on Photosystem II," K. M. Halverson and B. A. Barry, Biophys. J., 2003, 85, 1317-1325.
"Post-translational modifications in the CP43 subunit of photosystem II," L. B. Anderson, M. Maderia, A. J. A. Ouellette, C. Putnam-Evans, L. A. Higgins, T. Krick, M. MacCoss, H. Lim, J. R. Yates III, and B. A. Barry, Proceedings of the National Academy of Sciences, 2002, 99(23):14676-14681.
"His 190 and Glu 189 provide structural stabilization in Photosystem II," I. Pujols-Ayala and B. A. Barry, Biochemistry, 2002, 41, 11456-11465.
"X-ray scattering studies of the photosystem II manganese-stabilizing subunit," B. Svensson, D. Tiede, and B. A. Barry, J. Phys. Chem. B, 2002 106, 8485-8488 (Letter).
"Identification of spinach photosystem II light-harvesting components by tandem mass spectrometry," A. J. A. Ouellette and B. A. Barry, Photosyn. Res., 2002, 72, 159-173.
"An isotope-edited FT-IR study of a symporter, the lactose permease," J. Patzlaff, J. Zhang, R. Brooker, and B. A. Barry, Biochem., 2002, 41, 7366-7372.
"The spectroscopic properties of tyrosyl radicals in dipeptides," I. Ayala, K. Range, D. York, and B. A. Barry, J. Am. Chem. Soc., 2002, 124, 5496-5505.
"Modeling the active site of cytochrome oxidase: characterization of a cross-linked histidine-phenol," J. Cappuccio, I. Ayala, G. I. Elliott, I. Szundi, J. Lewis, J. P. Konopelski, B. A. Barry, and O. Einarsdottir, J. Am. Chem. Soc., 2002, 124, 1750-1760.