Robert "Bob" B Gennis

r-gennis@illinois.edu

A320 CLSL
Office: (217) 333-9075
Lab: (217) 333-4939
Fax: (217) 244-3186

Mail to: Department of Biochemistry
University of Illinois
600 S Goodwin Ave
A320 CLSL, MC-712
Urbana, IL 61801
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Robert "Bob" B Gennis

Professor of Biochemistry
Professor of Chemistry
Professor of Biophysics and Computational Biology
Affiliate, Beckman Institute
J. Woodland Hastings Endowed Chair

Research Topics

Archaea, Bioenergetics and Photosynthesis, Bioinformatics, Enzymology, Genetics, Membrane Biology, Microbial Ecology, Microbial Physiology, Molecular Evolution, Protein Structure

Education

B.S. 1966 University of Chicago
Ph.D. 1971 Columbia University
(Attended Albert Einstein College of Medicine in the M.D.-Ph.D. program, 1967-1968)
Postdoc. 1971-1973 with Dr. Jack Strominger, Harvard University

Membrane protein structure/function; Expression of membrane proteins from hyperthermophiles; Structure and mechanism of prokaryotic respiratory enzymes that generate a membrane potential

Our laboratory studies the structure and function of cytochrome oxidase and other membrane respiratory complexes with the goal to understand how electron transfer is coupled to the generation of a transmembrane proton electrochemical gradient. We are primarily interested in the structure and function of membrane proteins that are proton pumps. Our efforts are directed at several membrane enzymes that are components of bacterial respiratory or photosynthetic electron transport systems. Of principle interest are the members of the large respiratory oxidase superfamily known as the heme-copper oxidases. This superfamily includes the mammalian cytochrome c oxidase and many prokaryotic homologues. The structures of two enzymes in this superfamily have been determined to atomic resolution by X-ray diffraction techniques. The heme-copper oxidases caltalyze the reduction of O2 and utilize the free energy liberated by this reaction to pump protons electrogenically across the membrane bilayer (4 H+/O2). This generates transmembrane voltage and pH gradients, constituting the protonmotive force. The protonmotive force is used to drive ATP synthesis, active transport of solutes and other reactions. The structure of these enyzmes show two putative proton-conducting channels and we are interested in the roles of residues in these channels during the catalytic cycle.

The bacterial oxidases offer the opportunity to utilize the full array of molecular genetics techniques in combination with spectroscopic methods to address the catalytic mechanism of these enzymes. Single-turnover rapid kinetics techniques are being utilized to examine these questions using site-directed mutations in representative members of each of the three major families comprising the heme-copper oxidase superfamily. These include enzymes from E. coli, R. sphaeroides, T. thermophilus and V. cholerae. In addition, we are utilizing FTIR difference spectroscopy to identify specific amino acids directly engaged in the catalytic mechanism.

One set of mutants of particular interest are those which decouple oxidase activity from proton pumping. We are investigating these mutants as a new important tool to explore the mechanism of the proton pump.

In addition to the studies on the heme-copper oxidases, we are also examining other respiratory enzymes that generate a protonmotive force, including the cytochrome bd ubiquinol oxidase from E. coli. We are using techniques aimed at obtaining structural information, including X-ray diffraction, as well as examining aspects of the catalytic mechanisms of these enzymes.

Awards

Romano Scholar

Representative Publications

Chang, H. Y., Choi, S. K., Vakkasoglu, A. S., Chen, Y., Hemp, J., Fee, J. A., and Gennis, R. B. (2012) Exploring the proton pump and exit pathway for pumped protons in cytochrome ba3 from Thermus thermophilus, Proc Natl Acad Sci U S A 109, 5259-5264.

Lin, M. T., Baldansuren, A., Hart, R., Samoilova, R. I., Narasimhulu, K. V., Yap, L. L., Choi, S. K., O'Malley, P. J., Gennis, R. B., and Dikanov, S. A. (2012) Interactions of Intermediate Semiquinone with Surrounding Protein Residues at the Q(H) Site of Wild-Type and D75H Mutant Cytochrome bo(3) from Escherichia coli, Biochemistry 51, 3827-3838.

Lin, M. T., and Gennis, R. B. (2012) Product-controlled steady-state kinetics between cytochrome aa(3) from Rhodobacter sphaeroides and equine ferrocytochrome c analyzed by a novel spectrophotometric approach, Biochim Biophys Acta. 1817, 1894-1900.

Yildiz, A. A., Knoll, W., Gennis, R. B., and Sinner, E. K. (2012) Cell-free synthesis of cytochrome bo(3) ubiquinol oxidase in artificial membranes, Analytical biochemistry 423, 39-45.

von Ballmoos, C., Adelroth, P., Gennis, R. B., and Brzezinski, P. (2012) Proton transfer in ba(3) cytochrome c oxidase from Thermus thermophilus, Biochim Biophys Acta 1817, 650-657.

Nasvik Ojemyr, L., von Ballmoos, C., Gennis, R. B., Sligar, S. G., and Brzezinski, P. (2012) Reconstitution of respiratory oxidases in membrane nanodiscs for investigation of proton-coupled electron transfer, FEBS Lett 586, 640-645.

Nowak, C., Laredo, T., Gebert, J., Lipkowski, J., Gennis, R. B., Ferguson-Miller, S., Knoll, W., and Naumann, R. L. (2011) 2D-SEIRA spectroscopy to highlight conformational changes of the cytochrome c oxidase induced by direct electron transfer, Metallomics 3, 619-627.

Tang, M., Sperling, L. J., Berthold, D. A., Schwieters, C. D., Nesbitt, A. E., Nieuwkoop, A. J., Gennis, R. B., and Rienstra, C. M. (2011) High-resolution membrane protein structure by joint calculations with solid-state NMR and X-ray experimental data, J Biomol NMR 51, 227-233.

von Ballmoos, C., Gennis, R. B., Adelroth, P., and Brzezinski, P. (2011) Kinetic design of the respiratory oxidases, Proc Natl Acad Sci U S A 108, 11057-11062.

Borisov, V. B., Gennis, R. B., Hemp, J., and Verkhovsky, M. I. (2011) The cytochrome bd respiratory oxygen reductases, Biochim Biophys Acta 1807, 1398-1413.

Borisov, V. B., Murali, R., Verkhovskaya, M. L., Bloch, D. A., Han, H., Gennis, R. B., and Verkhovsky, M. I. (2011) Aerobic respiratory chain of Escherichia coli is not allowed to work in fully uncoupled mode, Proc Natl Acad Sci U S A 108, 17320-17324.

Egawa, T., Ganesan, K., Lin, M. T., Yu, M. A., Hosler, J. P., Yeh, S. R., Rousseau, D. L., and Gennis, R. B. (2011) Differential effects of glutamate-286 mutations in the aa(3)-type cytochrome c oxidase from Rhodobacter sphaeroides and the cytochrome bo(3) ubiquinol oxidase from Escherichia coli, Biochim Biophys Acta 1807, 1342-1348.

Han, H., Hemp, J., Pace, L. A., Ouyang, H., Ganesan, K., Roh, J. H., Daldal, F., Blanke, S. R., and Gennis, R. B. (2011) Adaptation of aerobic respiration to low O2 environments, Proc Natl Acad Sci U S A 108, 14109-14114.

Lee, H. J., Gennis, R. B., and Adelroth, P. (2011) Entrance of the proton pathway in cbb3-type heme-copper oxidases, Proc Natl Acad Sci U S A 108, 17661-17666.

Lin, M. T., Sperling, L. J., Frericks Schmidt, H. L., Tang, M., Samoilova, R. I., Kumasaka, T., Iwasaki, T., Dikanov, S. A., Rienstra, C. M., and Gennis, R. B. (2011) A rapid and robust method for selective isotope labeling of proteins, Methods 55, 370-378.

Complete Publications List