Building scaffolds in the cell's power stations

Building scaffolds in the cell's power stations
Left: In protein gels, the mitochondrial scaffold structure with many identical copies of Mic10 looks like a ladder. Right: Maria Bohnert and Martin van der Laan. Credit: © Wolfgang Fritz, University of Freiburg

A group of scientists led by Assistant Professor Dr. Martin van der Laan has decoded the molecular basis for the characteristic structures inside of mitochondria. Mitochondria are the powerhouses of cells and contain microscopic, strongly infolded membrane structures. These structures allow mitochondria to use the energy gained from food effectively. A defect in the architecture of mitochondrial membrane folds can lead to serious disorders in the nervous and muscular system. The team of researchers from the University of Freiburg has now published a study in the international professional journal Cell Metabolism in which it describes a sophisticated molecular structure made of membrane proteins. This structure allows mitochondria to develop their typical architecture while keeping the elaborate network of membrane folds stable.

A large complex of several protein components, called the MICOS complex (the acronym for mitochondrial contact site and cristae organizing system), plays a key role in the inner structure of mitochondria and was discovered by the same group of scientists from the University of Freiburg several years ago. For the current study, van der Laan's team worked together with researchers from the University of Groningen in the Netherlands and the Max-Planck-Institute of Biophysics in Frankfurt to decode the blueprint and functions of the MICOS. They determined that Mic10, which is a component of the MICOS, plays a central role. Dr. Maria Bohnert, an expert in molecular medicine and biochemistry from the University of Freiburg, discovered a structure within the protein Mic10 that functions like a barcode. It contains information that describes where Mic10 belongs within the cell. It thus controls the transport of Mic10 and its insertion into the system of mitochondria. When the protein has reached its final destination, a second characteristic structure of Mic10 enables it to join many identical copies together to create an extended protein scaffold that keeps the mitochondria's specialized membrane folds together.

If one of the two main structural elements in Mic10 is inactivated, parts of the membrane system collapse, leading to mitochondrial malfunction. On the other hand, if there is too much Mic10, an extreme expansion of the mitochondrial membrane folds occurs. "Our results show that Mic10 is the structural basis of MICOS. It is vital for building the small generators in the cell's power station," Bohnert said. These discoveries could help scientists better understand many different disorders related to the defective construction of and the partial loss of mitochondrial functions.

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Researchers discover a new basic principle of the mitochondria architecture

More information: Maria Bohnert, Ralf M. Zerbes, Karen M. Davies, Alexander W. Mühleip, Heike Rampelt, Susanne E. Horvath, Thorina Boenke, Anita Kram, Inge Perschil, Marten Veenhuis, Werner Kühlbrandt, Ida J. van der Klei, Nikolaus Pfanner, and Martin van der Laan: "Central Role of Mic10 in the Mitochondrial Contact Site and Cristae Organizing System", Cell Metabolism, published online 5 May 2015.
Journal information: Cell Metabolism

Provided by BIOSS - Centre for Biological Signalling Studies
Citation: Building scaffolds in the cell's power stations (2015, May 6) retrieved 19 July 2019 from
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May 06, 2015
WOW, combining this with the article from the other day that the structural folds are integral for the specialised roles a mitochondria take up in each different type of host cell, then it seems expression of Mic10 might be controlled by the HOST CELL??? So I wonder if a host cell encodes for Mic10, or if Mic10 is purely Mitochondrial. So what factors control the expression of Mic10 and its barcode sequence? I can't help but think that some of this mechanism lies in the HOST cell, and not the Mitochondria.

May 08, 2015
Jim, human mitochondria only codes 13 protein subunits, all critical parts of the main respiratory complex assemblies (cox, ATPsynthase,NADPH dehydrogenase, cytB) , http://medicalxpr...bad.html

May 08, 2015
@Johnhew, but it seems the efficiency of Catalysis is determined by the distance between folds. It also is apparent that mitochondria change shape to meet he needs of their host cell, somthing which I know you read just the other day.
So given that ALL human mitochondria encode for the protein subunits (as you said), then specialisation means some kind of epigenetics is at work, or antagonist/inhibitor. Surely this comes from the HOST cell, as the specialised mitochondrial folding is demonstrated in a CELL TYPE basis. Something is dictating the barcode in Mic10, which is dictating the fold distance, which dictates the catalyst efficiency.

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