- Member - Turkish Academy of Science
- Fellow - American Academy of Microbiology
- Fellow - American Association for the Advancement of Science
- DAAD Alumnus
Cell and Molecular Biology Graduate Group -http://www.med.upenn.edu/camb/faculty/mv/daldal.html
Biochemistry and Molecular Biophysics Graduate Group -http://www.med.upenn.edu/bmbgrad/Faculty/Master_List/Daldal/daldal.html
Daldal Research Group -
photosynthetic and respiratory electron transfer pathways and structure, function and biogenesis of cytochrome complexes
A schematic drawing of the photosynthetic and respiratory electron transport pathways and components of the facultative phototrophic bacterium Rhodobacter capsulatus. Download full (high-quality) PDF drawing.
We are interested in understanding the molecular basis of biological electron transfer during cellular energy transduction in photosynthesis and respiration. These basic metabolic pathways contain several multisubunit, membrane-bound protein complexes with various redox-active prosthetic groups. They are vital components for important cellular functions ranging from ATP synthesis to secretion, solute transport, motility and thermogenesis. Their dysfunction severely compromises cellular energy production, and leads to low crop yields in plants (photosynthesis), or neurological and muscular diseases in humans (respiration). A detailed understanding of how these evolutionarily well-conserved energy producing molecular machines perform their functions is of considerable biological significance and of general interest. Our studies aim to define the structure, function, assembly, biogenesis and regulation of these proteins in response to environmental signals, such as light and oxygen. Cytochrome bc1 complex and cytochrome cbb3 oxidase, which are membrane-associated proton pumps, and their physiological electron carriers the cytochromes c2 and cy are currently under study.
figure 2 - Ccm-system I components for c-type cytochrome maturation in purple bacteria.
All components of the c-type cyt maturation, except the thiol-disulfide oxidoreductase DsbA, are located in the cytoplasmic membrane. Both apocyt c and heme follow different routes to the heme ligation core complex, composed of CcmI, CcmH and CcmF. Apocyt c is translocated via the Sec pathway, its cysteine thiols in the conserved CXYCH motif are first oxidized by the DsbA- DsbB pathway, and then reduced by the cyt c maturation specific CcdA - CcmG and/or CcmH thio-reductive pathway. CcmI is involved in delivering apocyt c to the core heme ligation complex via its different domains. Heme is translocated across the membrane, possibly via ABCtype transporter CcmABCD, and is covalently attached to the conserved His residue of the heme chaperone CcmE. CcmC is involved in attaching heme to CcmE, and CcmD enhance holo-CcmE production. CcmA and CcmB promote the release of holo-CcmE from CcmC and CcmD. Upon formation of the thioether bonds between the apocyt c and heme vinyls, catalyzed by CcmH, CcmI and CcmF complex mature holocyt c is released. Download full (high-quality) PDF drawing.
We use molecular genetic and genomic approaches combined with biochemical, biophysical and structural techniques. As a model system, we use the purple non-sulfur photosynthetic bacterium Rhodobacter capsulatus instead of mitochondria of eukaryotes or chloroplasts of plants which are more refractory to multidisciplinary analyses. Current work is focused on the 1) structure and function of the functional sites of the cytochrome complexes and the assembly of their subunits and 2) biogenesis of c-type cytochromes including cyt cy and cyt cbb3 which are novel membrane-associated electron carriers recently discovered in our group.
Microbial Energy Transduction: Genetics, Structure and Function of Membrane Proteins. 1986. D. C. Youvan and F. Daldal, Eds. Cold Spring Harbor Laboratory Press, NY., USA.
The Purple Phototrophic Bacteria. 2008. C. N. Hunter, F. Daldal, M. C. Thurnauer and J. T. Beatty, Eds. Springer, Dordrecht, The Netherlands.
Recent Publications (2007-2009):
Sanders, C., C. Boulet and F. Daldal. (2007) Membrane-spanning and periplasmic segments of CcmI have distinct functions during cytochrome c biogenesis in Rhodobacter capsulatus. J. Bacteriol, 189: 789-800.
Aygun-Sunar S., Bilaloglu R., Golfine, H. and F. Daldal. (2007) Rhodobacter capsulatus Ornithine Lipid Biosynthesis Enzyme OlsA is Also Proficient for Phosphatidic Acid Biosynthesis. J. Bacteriol. 189: 8564-8574.
Onder, O, S, Turkarslan, D. Sun and F. Daldal. (2008) Overproduction or Absence of the Periplasmic Protease DegP Compromises Severely Bacterial Growth in the Absence of the Dithiol:Disulfide Oxidoreductase DsbA. Mol. Cell.Proteomics 7: 875-90.
Ozturk, Y., D-W. Lee, S. Mandaci, A., Osyczka, R. C. Prince and F. Daldal. (2008) Soluble variants of membrane-anchored cytochrome cy of Rhodobacter species are efficient photosynthetic electron carriers. J. Biol Chem. 283: 13964-13972.
Lee. D-W., Y. Ozturk, A., Osyczka, J. W. Cooley and F. Daldal. (2008) Cytochrome bc1-cy fusion complexes reveal the distance constraints for functional electron transfer between photosynthesis components. J. Biol. Chem. 283: 13973-13982.
Peters, A., Kulajta, C., Pawlik, G., Daldal, F. and H-G. Koch. (2008). Stability of the cbb3 type cyt. oxidase requires specific CcoQ-CcoP interactions. J. Bacteriol. 190: 5576-86.
Turkarslan, S., Sanders, C., Ekici, S. and F. Daldal. (2008). Compensatory Thio-redox Interactions between DsbA, CcdA and CcmG During Cytochrome c Maturation in Rhodobacter capsulatus. Molec Micro. 70: 652-666.
Sanders, C., Turkarslan, S., Lee, D-W., Onder, O., Kranz, R. G., and F. Daldal. (2008). The Cytochrome c Maturation Components CcmH, CcmI and CcmF Form a Multisubunit Membrane Complex in Rhodobacter capsulatus. J. Biol. Chem. 283: 29715-29722.
Zhang, Y., Lyver, E. R., Nakamaru-Ogiso, E., Yoon, H., Amutha, B., Lee, D-W., Bi, E., Ohnishi, T., Daldal, F., Pain, D. and Dancis, A. (2008). Dre2, a conserved eukaryotic Fe/S cluster protein, functions in cytosolic Fe/S protein biogenesis. Mol. Cell. Biol. 28: 5569-82.
Crowley, P. J., Berry, E. A., Cromartie, T., Daldal, F., Godfrey, C. R. A., Lee, D-W., Phillips, J. E., Taylor, A. and Viner, R. (2008). The role of molecular modeling in the design of analogues of the fungicidal natural products crocacins A and D. Bioorg. Med. Chem. 16: 10345-10355.
Cooley, J. W., Lee, D-W. and F. Daldal (2009). Across membrane communication between the Qo and Qi active sites of cytochrome bc1,Biochemistry, 48: 1888-1899.