Microtubule dynamics defects associated with hereditary spastic paraplegia

• Applicant: Privatdozent Dr. Günther Woehlke
• Subject Area: Biophysics
• Term: from 2008 to 2011
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 62195129

Neuronal degeneration has a multitude of causes, among others defective microtubule dynamics. We focus here on the molecular basis of defects caused by kinesin and spastin in hereditary spastic paraplegia (HSP) patients. In our proposal, we suggest investigating defective kinesins and spastins in vitro to identify the affected molecular processes. As patients are heterozygous for the mutations, it is important to study mixtures of intact and defective protein. Our proposal has two main parts. (i) We propose to characterize the motility of HSP kinesin mutants in vitro, and the effect on total cargo transport fluxes. To infer the effects on transport, we need to model transport, quantitatively predict the effects of mutants, and verify the predictions in experiments, possibly animal models. (ii) We propose to investigate the ATP-dependent microtubule-severing enzyme spastin, which is mutated in the majority of HSP patient families. We want to elucidate the kinetic cycle, and measure mechanical forces produced by this AAA ATPase. To mimic the situation in heterozygous patients, we propose to study the effects of known HSP spastin mutations in heterogeneous mixtures of wildtype and mutant spastin subunits.

• DFG Programme: Research Grants