Stabilizing Protein-Protein-Interactions with Multivalent Ligands

Huntington’s disorder (HD) is one of the neurodegenerative disorders in which the polyglutamine (polyQ) tract of the protein huntingtin (htt) is found to be expanded. First exon of this mutant htt protein is found in the inclusions in the brain of the patient suffering from HD, which is the pathological hallmark of the disease1. Exon-1 of htt comprises of 17 amino acid long N-terminal helix (Nt17), polyQ tract in between and polyP-rich C-terminal. Nt17 has been reported to selfassociate and enhance the rate of mutant htt aggregation which leads to protein aggregation resulting in the inclusion formation. The lysine residues K6 and K15 in Nt17 are thought to be involved in inter helical association and are proposed to form the template for initial oligomerization2. To prevent these specific residues from interacting, we have utilized a lysine specific molecular tweezer (MT) 3. Here, we have studied the effect of MT on the structure and oligomerization process of the mutant htt. By MD simulations and CD spectroscopy we are able to show the disruption of the helical structure. A FRET based aggregation assay showed that the MT is effective in inhibiting mutant htt aggregation. References: 1. Rubinsztein, D. C., J. Leggo, et al. "Phenotypic characterization of individuals with 30–40 CAG repeats in the Huntington disease (HD) gene reveals HD cases with 36 repeats and apparently normal elderly individuals with 36–39 repeats." American journal of human genetics. 1996 59(1): 16. 2. Arndt, J. R., R. J. Brown, et al. "Lysine residues in the N‐terminal huntingtin amphipathic α‐helix play a key role in peptide aggregation." Journal of Mass Spectrometry 2015 50(1): 117-126. 3. Zheng, X., D. Liu, et al. "Amyloid β-Protein Assembly: The Effect of Molecular Tweezers CLR01 and CLR03." The Journal of Physical Chemistry B 2015 119(14): 4831-4841.