Motion in Cytochrome c oxidoreductase (bc1 complex) [bc1]

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Classification Known Domain Motion, Hinge Mechanism [D-h-2]

Structures 1BCC chicken 1BE3 1BGY 1QCR 2BCC chicken (stigmatellin-bound) 3BCC chicken (UHDBT-bound)

Description Native structures of bc1 complex was solved by Xia et al. from bovine source, and by Zhang et al. from chicken source. Although most of the complexes occupy equivalent positions in the two structures, the positions of the [2Fe-2S] centers of the Rieske subunit (ISP, or iron sulfur protein) are different. There is a 16-22 angstrom displacement of the [2Fe-2S] cluster and the C-terminal extrinsic domain of the ISP between the two strtuctures. In the bovine structure (PDB 1QCR), the [2Fe-2S] cluster is found to be close to cyt b and distant from cyt c1, whereas in the chicken structure (PDB 1BCC), the ISP is close to cyt c1 and distant from cyt b. In chicken complex, Zhang et al. also observed that Qo-site inhibitor stigmatellin or UHDBT (PDB 2BCC, 3BCC) induces a displacement of the ISP from its natuve position close to cyt c1, to a position close to that observed in the Xia et al. structure. Such movement invloves ligand formation between His-161 of the [2Fe-2S] binding cluster and the inhibitor. A third "intermediate" position between cyt c1 and cyt b was also identified in one type of bovine crystal (PDB 1BGY 1BE3) by Iwata et al.. In none of the strcutures is the complex in a configuration could be competent in all partial reactions of quinol oxidation. However, in each of the two main positions, the configuration could function for a part of the reaction cycle. It was suggested that the different crystal structures reflect a movement of the ISP extrinsic domain between two positions, which is necessary for electron transfer. This movement can be characterized as a rotational displacement of about 57 degrees (65 degrees in bovine structures), while the N-terminal membrane anchor is fixed and the action occurs in a short linker region between the membrane anchor and the extrinsic domain. The mobile extrinsic domain retains essentially the same tertiary structure, and the anchoring N-terminal tail remains in the same position. Such "domain shuttle" mechanism has been supported by mutation studies in Rhodobacter sphaeroide, when decreasing of bc1 activity were observed after increasing the rigidity of the short linker region of Rieske protein described above.

Particular values describing motion Creation Date = 19971130 Experimental Methods = x (Traditional x-ray) Maximum CA displacement (A) = 16 ((from submission)) Maximum Rotation (degrees) = 57 Modification Date = 2000-12-12 18:42:49.000

References Crofts, A.R., Guergova-Kuras, M., Huang, L.-S., Kuras, R., Zhang, Z. and Berry, E.A. The mechanism of ubiquinol oxidation by the bc1 complex: the role of the iron sulfur protein, and its mobility. Biochemistry 38, 15791-15806, (1999) [Medline info for 20093123] Iwata, S., Lee, J.W., Okada, K., Lee, J.K., Iwata, M., Rasmussen, B., Link, T.A., Ramaswamy, S., Jap, B.K. Science 281:64-71, (1998). [Medline info for 98316377] Xia, D., Yu, C. -A., Kim, H., Xia, J. -Z., Kachurin, A.M., Zhang, L., Yu, L., Deisenhofer, J. Science 277: 60-66, (1997). [Medline info for 97349328] Zhang, Z., Huang, L.-S., Shulmeister V.-M., Chi, Y.-I., Kim, K.K., Hung, L.-W., Crofts, A.R., Berry, E.A. and Kim, S.-H. Nature 392:677-684, (1998). [Medline info for 98224700]

Data and Graphics Custom morphs Large MPEG movies of the entire complex Further Information Bc-1 complex homepage (via UIUC) Coordinate Coordinate data for bc1 complex Papers Online paper collected by Crofts Motion in Chime showing the expected movement (via UIUC 0.9 MB) Motion in an annotated animated GIF movie via UIUC, 4MB Motion in an annotated AVI movie via UIUC, ~6.7 MB

GO terms associated with structures Molecular function electron transporter activity, metalloendopeptidase activity, heme binding, oxidoreductase activity, ubiquinol-cytochrome-c reductase activity Cellular component ubiquinol-cytochrome-c reductase complex (sensu Eukaryota), mitochondrial electron transport chain, membrane, ubiquinol-cytochrome-c reductase complex, mitochondrial membrane Biological process proteolysis and peptidolysis, mitochondrial electron transport, ubiquinol to cytochrome c, electron transport

Morphs

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Best representative Morph Morph name Structure #1 Structure #2 Residues [ ] [ ]

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Copyright 1995-2005 M. Gerstein, W. Krebs, S. Flores, N. Echols, and others
Email: Mark.Gerstein _at_ yale.edu