ScienceDaily (July 2, 2010) — Scientists of the University of Freiburg and the University of Frankfurt have elucidated the architecture of the largest protein complex of the cellular respiratory chain.They discovered an unknown mechanism of energy conversion in this molecular complex. The mechanism is required to utilize the energy contained in food.
The structural model of mitochondrial complex I provides new insights in energy conversion at nanoscale. A molecular coupling device links pump modules in the membrane arm of the huge enzyme complex.
(Credit: Image courtesy of Albert-Ludwigs-Universität Freiburg)
A detailed understanding of the function of complex I is of special medical interest. Dysfunction of the complex is implicated in several neurodegenerative diseases such as Parkinson´s disease or Alzheimer´s disease, and also with the physiological processes of biological aging, in general. The work of Prof. Carola Hunte of the Freiburg Institute for Biochemistry and Molecular Biology and the Freiburg excellence centre BIOSS (Centre for Biological Signalling Studies) in cooperation with Prof. Ulrich Brandt, Professor for Molecular Bioenergetics and member of the excellence centre „Macromolecular Complexes" and Dr. Volker Zickermann of his research group is a major step forward to this understanding.
The energy metabolism takes place in the so-called powerhouses of the cell, the mitochondria. They transduce the energy taken up as food into adenosine triphosphate, in short ATP, which is the universal energy currency of life. A chain of five complicated molecular machines in the mitochondrial membrane are responsible for the energy conversion. The production of ATP in mitochondria requires so many steps, as it is in principal a Knallgasreaction. In a laboratory experiment, hydrogen and oxygen gas would react in an explosion and the energy contained would be released as heat. In biological oxidation, the energy will be released by the membrane bound protein complexes of the respiratory chain in a controlled manner in small packages. Comparable to a fuel cell, this process generates an electrical membrane potential, which is the driving force of ATP synthesis. The total surface of all mitochondrial membranes in a human body covers about 14.000 square meter. This accounts for a daily production of about 65 kg of ATP.
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Science DOI: 10.1126/science.1191046
Functional Modules and Structural Basis of Conformational Coupling in Mitochondrial Complex ICarola Hunte,1,2, 3,* Volker Zickermann,4,* Ulrich Brandt4,
Proton-pumping respiratory complex I is among the largest and most complicated membrane protein complexes. Its function is critical for efficient energy supply in aerobic cells and malfunctions are implicated in many neurodegenerative disorders. Here, we report the x-ray crystallographic analysis of mitochondrial complex I. The positions of all iron-sulfur clusters relative to the membrane arm were determined in the complete enzyme complex.The ubiquinone reduction site resides close to 30 Å above the membrane domain. The arrangement of functional modules suggests conformational coupling of redox chemistry with proton pumping and essentially excludes direct mechanisms. We suggest that a ~60 Å long helical transmission-element is critical for transducing conformational energy to proton-pumping elements in the distal module of the membrane arm.
1 Centre for Biological Signalling Studies (BIOSS), Institute for Biochemistry and Molecular Biology, University of Freiburg, Frieburg, Germany.
2 Institute of Membrane and Systems Biology, University of Leeds, Leeds, UK.
3 Department of Molecular Membrane Biology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany.
4 Molecular Bioenergetics Group, Medical School, Cluster of Excellence Frankfurt "Macromolecular Complexes," Center for Membrane Proteomics, Goethe-University, Frankfurt am Main, Germany.
* These authors contributed equally to this work.
To whom correspondence should be addressed. E-mail: brandt@zbc.kgu.de
Received for publication 16 April 2010. Accepted for publication 10 June 2010.
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NOTA TRIUNFANTE DESTE BLOGGER:
Cada vez mais pesquisadores encontram complexidade na natureza. Cada vez mais ele escrevem seus abstracts com linguagem teleológica. Cada vez mais corroboram as teses propostas de que sinais de inteligência são empiricamente detectados na natureza.
E ainda têm a cara de pau de dizer que a teoria do Design Inteligente é pseudociência e impede o avanço da ciência. Quem impede o avanço da ciência, caras-pálidas??? É a teoria da evolução reducionista de Darwin, e não o Design Inteligente.
E ainda têm a cara de pau de dizer que a teoria do Design Inteligente é pseudociência e impede o avanço da ciência. Quem impede o avanço da ciência, caras-pálidas??? É a teoria da evolução reducionista de Darwin, e não o Design Inteligente.
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