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Magnus Kjærgaard

Flexible proteins in the molecular mechanism of memory

Consciousness and mental processes arise from physical and chemical processes in the brain. Understanding how this occurs at the molecular level is one of the grand challenges for science in the 21st century.

Our research investigates the mechanism by which information is encoded into and stored in the physical structure of the brain. The paradigmatic model for molecular memory is synaptic plasticity, where communication across a synapse alters the sensitivity of the synapse. Synaptic plasticity is known to be mediated by neurotransmitter receptors and enzymes in the post-synaptic density. We are studying NMDA-type glutamate receptor, focusing on their intrinsically disordered intra-cellular domains and their involvement in synaptic plasticity.

 

Effective concentrations in macromolecular complexes

In the cell, many macromolecules are organised into large complexes. The physical association of molecules alter the equilibrium of e.g. enzyme:substrate interactions by controlling the effective concentration. Despite of its importance, effective concentrations in biomolecular complexes are poorly understood. We develop methods to experimentally determine effective concentrations of biomolecules joined by flexible linkers, and use this data to rationalise how the properties of the linker determine effective concentratio. Our goal is to understand how effective concentrations can direct signalling pathways using kinase-scaffolding proteins.

 

 

Research topics

Our research centers on the biological functions of protein dynamis. Currently, we study two biochemical problems described in more detail below: i) Understanding the role of flexible proteins in the molecular basis of memory  and ii) Quantifying and predicting effective cocentrations in supra-molecular complexes.  Methodologically, we use whatever methods needed to answer biological question at hand but have a special expertise in solution NMR spectroscopy and single molecule FRET techniques.

Our research is currently supported by the Villum Foundation, Aarhus Institute of Advanced Studies and the Lundbeck Foundation.

Peer-reviewed publications

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Kjærgaard, M., Nørholm, A.-B., Hendus-Altenburger, R., Pedersen, S. F., Poulsen, F. M. & Kragelund, B. B. (2010). Temperature-dependent structural changes in intrinsically disordered proteins: formation of alpha-helices or loss of polyproline II? Protein Science, 19(8), 1555-64. https://doi.org/10.1002/pro.435
Kjærgaard, M., Hansen, L. V., Jacobsen, B., Gardsvoll, H. & Ploug, M. (2008). Structure and ligand interactions of the urokinase receptor (uPAR). Frontiers in Bioscience, 13, 5441-61.
Kjærgaard, M., Gårdsvoll, H., Hirschberg, D., Nielbo, S., Mayasundari, A., Peterson, C. B., Jansson, A., Jørgensen, T. J. D., Poulsen, F. M. & Ploug, M. (2007). Solution structure of recombinant somatomedin B domain from vitronectin produced in Pichia pastoris. Protein Science, 16(9), 1934-45. https://doi.org/10.1110/ps.072949607
Kjaergaard, M. & Kragelund, B. B. (2017). Functions of intrinsic disorder in transmembrane proteins. Cellular and Molecular Life Sciences, 74(17), 3205-3224. https://doi.org/10.1007/s00018-017-2562-5
Kjaergaard, M., Dear, A. J., Kundel, F., Qamar, S., Meisl, G., Knowles, T. P. J. & Klenerman, D. (2018). Oligomer diversity during the aggregation of the repeat-region of tau. ACS Chemical Neuroscience, 9(12), 3060-3071. https://doi.org/10.1021/acschemneuro.8b00250
Kjaergaard, M., Glavina, J. & Chemes, L. B. (2021). Predicting the effect of disordered linkers on effective concentrations and avidity with the “Ceff calculator” app. In M. Merkx (Ed.), Linkers in Biomacromolecules (pp. 145-171). Academic Press. https://doi.org/10.1016/bs.mie.2020.09.012
Kjaergaard, M., Petersen, N. C., Sørensen, J. B. & Takeuchi, T. (2021). Introducing the special issue on “Proteins and Circuits in Memory”. European Journal of Neuroscience, 54(8), 6691-6695. https://doi.org/10.1111/ejn.15491