International Collaboration in Chemistry:ELECTRONIC STRUCTURE OF BIOLOGICAL METALLO-CLUSTER AND ITS MAGNETIC INTERPLAY WITH THE PROTEIN SURROUNDING IN THERMOPHILE METALLOENZYMES

University Of Illinois At Urbana-Champaign, Urbana IL

Investigators

Abstract

This International Collaboration in Chemistry (ICC) award in the Chemistry of Life Processes (CLP) program in the Division of Chemistry supports work by Professor Sergei Dikanov from the University of Illinois at Urbana-Champaign, in collaboration with Dr. Toshio Iwasaki of Nippon Medical School, Japan, and Dr. Takashi Kumasaka of Japan Synchrotron Radiation Research Institute (JASRI)/SPring-8, to study the influence of the protein environment on the electronic structure of the reduced [2Fe-2S] clusters, in which the ligands to the iron(II) site can be (Cys)2, (His)1(Cys)1, or (His)2. This project will explore the complete three-dimensional landscape of the unpaired spin density distribution over the cluster and neighboring key amino acid residues in order to identify the residues having the major influence on the electronic structure of the reduced [2Fe-2S] cluster in hyperthermophilic tractable iron-sulfur proteins. To achieve the goal, a complementary set of multifrequency pulsed EPR approaches will be applied to wild-type proteins, using frozen solutions and single-crystals, and to proteins with uniform and site-specific stable isotopic (2H, 15N, 13C, 57Fe) substitution. The spectroscopic approaches will be combined with ultrahigh-resolution X-ray crystallography, and theoretical calculations. This project will provide excellent training opportunities to young scientists who will gain invaluable multidisciplinary international research experience via bidirectional visits. This project is jointly supported by the NSF and the Japan Society for the Promotion of Science (JSPS). All major electron transfer chains incorporate iron-sulfur clusters, and the environment of the cluster is the main determinant of the redox and/or catalytic activity. Their roles in catalysis of energy conversion are of central importance in photosynthesis, respiration, and many ancillary metabolic processes. Our understanding of these determinants is essential to a deeper knowledge how these processes work, and of critical importance in knowing how to optimize such processes, for example in generation of biofuels.