This subproject is one of many research subprojects utilizing theresources provided by a Center grant funded by NIH/NCRR. The subproject andinvestigator (PI) may have received primary funding from another NIH source,and thus could be represented in other CRISP entries. The institution listed isfor the Center, which is not necessarily the institution for the investigator.Oxygen, that supports all aerobic life, is abundant in the atmosphere because of its constant regeneration by photosynthetic water oxidation by green plants, algae, and cyanobacteria. This light-requiring reaction is catalyzed by a Mn4Ca cluster associated with photosystem II (PS II). In our ongoing investigations of the Mn oxidation-state changes, the structure and the associated cofactors Ca and Cl and the mechanism of water oxidation, we are using the BioCAT beamline to conduct X-ray absorption and emission spectroscopy experiments that are at present not possible elsewhere. We have shown the feasibility of the range-extended EXAFS method and collected data without interference from Fe in the PS II sample. The improvement in the k-space data and the Fourier transform is striking. We can now resolve two short Mn-Mn distances in the S (subscript)1 and S (subscript)2 states; while earlier we could discern only one distance of ~2.7 . We have also collected range-extended EXAFS data using oriented PS II membranes, and it is quite clear that the heterogeneity is more obvious. These results which provide important information about the structure of the water oxidizing Mn complex are in press in J. Biol. Chem. and this publication has been selected as the paper of the week with a cover figure. We have extended these studies to the S (subscript)0 and S (subscript)3 intermediate states of the enzymatic cycle, and the preliminary results show that there is a significant change in the structure of the Mn complex in the S (subscript)3 state. This result has important implications for choosing between the many mechanisms that have been proposed for the water oxidation reaction.

National Institute of Health (NIH)
National Center for Research Resources (NCRR)
Biotechnology Resource Grants (P41)
Project #
Application #
Study Section
Special Emphasis Panel (ZRG1-BCMB-E (40))
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Illinois Institute of Technology
Other Basic Sciences
Schools of Arts and Sciences
United States
Zip Code
Orgel, Joseph P R O; Sella, Ido; Madhurapantula, Rama S et al. (2017) Molecular and ultrastructural studies of a fibrillar collagen from octocoral (Cnidaria). J Exp Biol 220:3327-3335
Yazdi, Aliakbar Khalili; Vezina, Grant C; Shilton, Brian H (2017) An alternate mode of oligomerization for E. coli SecA. Sci Rep 7:11747
Sullivan, Brendan; Robison, Gregory; Pushkar, Yulia et al. (2017) Copper accumulation in rodent brain astrocytes: A species difference. J Trace Elem Med Biol 39:6-13
Morris, Martha Clare (2016) Nutrition and risk of dementia: overview and methodological issues. Ann N Y Acad Sci 1367:31-7
Robison, Gregory; Sullivan, Brendan; Cannon, Jason R et al. (2015) Identification of dopaminergic neurons of the substantia nigra pars compacta as a target of manganese accumulation. Metallomics 7:748-55
Gelfand, Paul; Smith, Randy J; Stavitski, Eli et al. (2015) Characterization of Protein Structural Changes in Living Cells Using Time-Lapsed FTIR Imaging. Anal Chem 87:6025-31
Liang, Wenguang G; Ren, Min; Zhao, Fan et al. (2015) Structures of human CCL18, CCL3, and CCL4 reveal molecular determinants for quaternary structures and sensitivity to insulin-degrading enzyme. J Mol Biol 427:1345-1358
Zhou, Hao; Li, Shangyang; Badger, John et al. (2015) Modulation of HIV protease flexibility by the T80N mutation. Proteins 83:1929-39
Nobrega, R Paul; Arora, Karunesh; Kathuria, Sagar V et al. (2014) Modulation of frustration in folding by sequence permutation. Proc Natl Acad Sci U S A 111:10562-7
Jiao, Lianying; Ouyang, Songying; Shaw, Neil et al. (2014) Mechanism of the Rpn13-induced activation of Uch37. Protein Cell 5:616-30

Showing the most recent 10 out of 100 publications