Significance of Knotted Structures for Function of Proteins and Nucleic Acids - September 17-21, 2014

Significance of Knotted Structures for Function of Proteins and Nucleic Acids

Poster Session I

10 – POS Board 10 Mechanical Analysis of Disordered Proteins: Accessing a Third of the Proteome Gómez-Sicilia, Àngel 1 , Chwastyk, Mateusz 2 , Galea-Prat, Albert 1 , Sikora, Mateusz 2,3, Carrión-Vázquez, Mariano 1 & Cieplak, Marek 2 . 1 Instituto Cajal /CSIC & IMDEA Nanociencias, Madrid, Spain. 2 Laboratory of Biological Physics, Institute of Physics, Polish Academy of Sciences,Warsaw, Poland. 3 Institut of Science and Technology Austria, Klosterneuburg, Austria. With the advent of single molecule force spectroscopy, many proteins could be examined in order to uncover the distribution of their mechanical stabilities. However proteins with low or polymorphic mechanostability could not be unequivocally studied due to the fact that this technique establishes a hierarchy in which the low-stability structures tend to unfold first, where they can be mixed with unspecific interactions in the so-called proximal region. Intrinsically disordered proteins (IDPs) belong to this class of proteins, represent more than one third of the eukaryotic proteome and many are heavily involved in a variety of diseases. In order to study the mechanical properties of IDPs, we have developed a mechanical-protection strategy where the protein under study is inserted inside a more resistant one, which will unfold far from the proximal region where signal is no longer masked by non-specific noise. Thanks to this strategy, we have been able to study the rich conformational polymorphism involved in proteins associated with amyloidogenic neurodegenerative diseases such as Alzheimer's or Huntington's. As a test for this experimental strategy, we also examined in silico different possible combinations for the protector (host) and protected (guest) molecules using a structurebased model and compared them to serially connected proteins. Our results show that the mechanical protection technique works for all the cases and the mechanostability of the guest is preserved. Also, this method proves that an optimized strategy would be one in which the single-molecule markers flanking the host molecule have a much lower mechanostability than the host, so that the unfolding order in the recording is marker, host, guest and therefore the signal of interest is never mixed with the makers.

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