Book of Abstracts: Albany 2011

category image Albany 2011
Conversation 17
June 14-18 2011
©Adenine Press (2010)

Illuminating the Mitochondrial Scission Machinery

Dynamin-related proteins (DRPs) function in mitochondrial and peroxisomal divison, probably by regulating membrane fission in a concerted manner with a number of accessory proteins which are believed to recruit DRPs to the organelle membrane. Time-lapse confocal microscopy of living cells shows that mitochondria are remarkably mobile and plastic organelles, constantly changing their shape, fusing with one another and then separating again, thereby comprising a tubulovesicular network throughout the entire cell. Perturbation of this dynamic process has been implicated in a number of neurological disorders such as Alzheimer’s disease, Parkinson’s disease, hereditary optic atrophy, and Charcot-Marie-Tooth neuropathy.

The proteins maintaining the organization of the mitochondrial network also actively participate in induction of the intrinsic pathway of apoptosis that is regulated by mitochondria when cytochrome c is released. Although many proteins involved in mitochondrial fission and fusion events have been discovered in the last decade, the mechanism of the synchronized splitting and fusion of the two membrane system of mitochondria remains vague, not least because there are currently no structural data regarding the proteins involved.

In this study, a protein related to mitochondrial fission, human dynamin-like protein 1 (DNM1L), is being investigated. The goal of this work is to elucidate the structure of DNM1L in order to shed light on mitochondrial dynamics and to contribute to our understanding of the mechanism of action of the dynamin superfamily of proteins. More than 20 different DNM1L constructs were expressed in large scale to obtain sufficient amounts of protein for crystallisation trials and biochemical experiments. The circular dichroism spectrum of purified wild type DNM1L shows a mostly α-signal, though with some β-sheet contribution. Preliminary biochemical characterization showed – as is typical for large GTPases – a low affinity for both GDP and GTP. Crystallization trials are in progress.

Chris Fröhlich1,2
Oliver Daumke1,3

1 Max-Delbrück-Centrum
Molecular Medicine, Crystallography,
Robert-Rössle2Strasse 10,
13125 Berlin, Germany
2 Institute for Chemistry and Biochemistry,
Freie Universität Berlin,
Takustrasse 3
14195 Berlin, Germany
3 Institute of Medical Physics and Biophysics,
Charité, Ziegelstrasse 5-9,
10117 Berlin, Germany