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Sarr M, Kronqvist N, Chen G, Aleksis R, Purhonen P, Hebert H, Jaudzems K, Rising A, Johansson J. A spidroin-derived solubility tag enables controlled aggregation of a designed amyloid protein. FEBS J 2018; 285:1873-1885. [PMID: 29604175 DOI: 10.1111/febs.14451] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 03/08/2018] [Accepted: 03/26/2018] [Indexed: 12/31/2022]
Abstract
Amyloidogenesis is associated with more than 30 diseases, but the molecular mechanisms involved in cell toxicity and fibril formation remain largely unknown. The inherent tendency of amyloid-forming proteins to aggregate renders expression, purification, and experimental studies challenging. NT* is a solubility tag derived from a spider silk protein that was recently introduced for the production of several aggregation-prone peptides and proteins at high yields. Herein, we investigate whether fusion to NT* can prevent amyloid fibril formation and enable controlled aggregation for experimental studies. As an example of an amyloidogenic protein, we chose the de novo-designed polypeptide β17. The fusion protein NT*-β17 was recombinantly expressed in Escherichia coli to produce high amounts of soluble and mostly monomeric protein. Structural analysis showed that β17 is kept in a largely unstructured conformation in fusion with NT*. After proteolytic release, β17 adopts a β-sheet conformation in a pH- and salt-dependent manner and assembles into amyloid-like fibrils. The ability of NT* to prevent premature aggregation and to enable structural studies of prefibrillar states may facilitate investigation of proteins involved in amyloid diseases.
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Affiliation(s)
- Médoune Sarr
- Division for Neurogeriatrics, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Huddinge, Sweden
| | - Nina Kronqvist
- Division for Neurogeriatrics, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Huddinge, Sweden
| | - Gefei Chen
- Division for Neurogeriatrics, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Huddinge, Sweden
| | - Rihards Aleksis
- Department of Physical Organic Chemistry, Latvian Institute of Organic Synthesis, Riga, Latvia
| | - Pasi Purhonen
- Department of Biosciences and Nutrition, Karolinska Institutet, and School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Huddinge, Sweden
| | - Hans Hebert
- Department of Biosciences and Nutrition, Karolinska Institutet, and School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Huddinge, Sweden
| | - Kristaps Jaudzems
- Department of Physical Organic Chemistry, Latvian Institute of Organic Synthesis, Riga, Latvia
| | - Anna Rising
- Division for Neurogeriatrics, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Huddinge, Sweden.,Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Jan Johansson
- Division for Neurogeriatrics, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Huddinge, Sweden
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Abstract
A numerical study of the energy landscape of the space of model proteinsequences is carried out. As a consequence of the heterogeneity of thecontact energies among amino acids, the energy landscape displays a veryrough profile, a behaviour typical of frustrated systems. This givesraise to a hierarchical clustering of low-energy sequences and can have evolutionary consequences.
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Affiliation(s)
- G Tiana
- The Niels Bohr Institute, University of Copenhagen, Bledgamsvej 16, 2100 Copenhagen, Denmark ; Department of Chemistry, Harvard University, 16 Oxford st., Cambridge, MA USA
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