Gómez Sicilia, Àngel; Sikora, Mateusz KISTA; Cieplak, Marek; Carrión Vázquez, Mariano
Deposits of misfolded proteins in the human brain are associated with the development of many neurodegenerative diseases. Recent studies show that these proteins have common traits even at the monomer level. Among them, a polyglutamine region that is present in huntingtin is known to exhibit a correlation between the length of the chain and the severity as well as the earliness of the onset of Huntington disease. Here, we apply bias exchange molecular dynamics to generate structures of polyglutamine expansions of several lengths and characterize the resulting independent conformations. We compare the properties of these conformations to those of the standard proteins, as well as to other homopolymeric tracts. We find that, similar to the previously studied polyvaline chains, the set of possible transient folds is much broader than the set of known-to-date folds, although the conformations have different structures. We show that the mechanical stability is not related to any simple geometrical characteristics of the structures. We demonstrate that long polyglutamine expansions result in higher mechanical stability than the shorter ones. They also have a longer life span and are substantially more prone to form knotted structures. The knotted region has an average length of 35 residues, similar to the typical threshold for most polyglutamine-related diseases. Similarly, changes in shape and mechanical stability appear once the total length of the peptide exceeds this threshold of 35 glutamine residues. We suggest that knotted conformers may also harm the cellular machinery and thus lead to disease.
PLoS Computational Biology
We acknowledge the support by the EU Joint Programme in Neurodegenerative Diseases (JPND AC14/00037) project. The project is supported through the following funding organisations under the aegis of JPND—www.jpnd.eu: Ireland, HRB; Poland, National Science Centre; and Spain, ISCIII.
Gómez Sicilia À, Sikora MK, Cieplak M, Carrión Vázquez M. An exploration of the universe of polyglutamine structures. PLoS Computational Biology. 2015;11(10). doi:10.1371/journal.pcbi.1004541
Gómez Sicilia, À., Sikora, M. K., Cieplak, M., & Carrión Vázquez, M. (2015). An exploration of the universe of polyglutamine structures. PLoS Computational Biology. Public Library of Science. https://doi.org/10.1371/journal.pcbi.1004541
Gómez Sicilia, Àngel, Mateusz K Sikora, Marek Cieplak, and Mariano Carrión Vázquez. “An Exploration of the Universe of Polyglutamine Structures.” PLoS Computational Biology. Public Library of Science, 2015. https://doi.org/10.1371/journal.pcbi.1004541.
À. Gómez Sicilia, M. K. Sikora, M. Cieplak, and M. Carrión Vázquez, “An exploration of the universe of polyglutamine structures,” PLoS Computational Biology, vol. 11, no. 10. Public Library of Science, 2015.
Gómez Sicilia À, Sikora MK, Cieplak M, Carrión Vázquez M. 2015. An exploration of the universe of polyglutamine structures. PLoS Computational Biology. 11(10), e1004541.
Gómez Sicilia, Àngel, et al. “An Exploration of the Universe of Polyglutamine Structures.” PLoS Computational Biology, vol. 11, no. 10, e1004541, Public Library of Science, 2015, doi:10.1371/journal.pcbi.1004541.
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