Bulletin of the American Physical Society
APS March Meeting 2013
Volume 58, Number 1
Monday–Friday, March 18–22, 2013; Baltimore, Maryland
Session T11: Invited Session: Self-Assembly, Physical Properties and Functionalities of Amyloid Fibrils |
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Sponsoring Units: DPOLY DBIO Chair: Raffaele Mezzenga, ETH-Zurich Room: 310 |
Thursday, March 21, 2013 8:00AM - 8:36AM |
T11.00001: Folding and mis-folding of proteins Invited Speaker: Christopher Dobson |
Thursday, March 21, 2013 8:36AM - 9:12AM |
T11.00002: Molecular Self-Assembly of Short Aromatic Peptides: From Biology to Nanotechnology and Material Science Invited Speaker: Ehud Gazit The formation of ordered amyloid fibrils is the hallmark of several diseases of unrelated origin. In spite of grave clinical consequence, the mechanism of amyloid formation is not fully understood. We have suggested, based on experimental and bioinformatic analysis, that aromatic interactions may provide energetic contribution as well as order and directionality in the molecular-recognition and self-association processes that lead to the formation of these assemblies. This is in line with the well-known central role of aromatic-stacking interactions in self-assembly processes. Our works on the mechanism of aromatic peptide self-assembly, lead to the discovery that the diphenylalanine recognition motif self-assembles into peptide nanotubes with a remarkable persistence length. Other aromatic homodipeptides could self-assemble in nano-spheres, nano-plates, nano-fibrils and hydrogels with nano-scale order. We demonstrated that the peptide nanostructures have unique chemical, physical and mechanical properties including ultra-rigidity as aramides, semi-conductive, piezoelectric and non-linear optic properties. We also demonstrated the ability to use these peptide nanostructures as casting mold for the fabrication of metallic nano-wires and coaxial nano-cables. The application of the nanostructures was demonstrated in various fields including electrochemical biosensors, tissue engineering, and molecular imaging. Finally, we had developed ways for depositing of the peptide nanostructures and their organization. We had use inkjet technology as well as vapour deposition methods to coat surface and from the peptide ``nano-forests''. We recently demonstrated that even a single phenylalanine amino-acid can form well-ordered fibrilar assemblies.\\[4pt] References: Reches, M. and Gazit, E. (2003) Casting Metal Nanowires within Discrete Self-Assembled Peptide Nanotubes. \textbf{Science} \textit{300}, 625-627. Reches, M. and Gazit, E. (2006) Controlled Patterning of Aligned Self-Assembled Peptide Nanotubes. \textbf{Nature Nanotechnol.} \textit{1}, 195-200. Adler-Abramovich L., Aronov D., Beker P., Yevnin M., Stempler S., Buzhansky L., Rosenman G. and Gazit E. (2009) Self-Assembled Arrays of Peptide Nanotubes by Vapour Deposition. \textbf{Nature Nanotechnol.} \textit{4}, 849-854. Carny, O., Shalev, D., and Gazit, E. (2006) Fabrication of Coaxial Metal Nanowires Using Self-Assembled Peptide Nanotube Scaffold. \textbf{Nano Lett.}\textit{ 6}, 1594-1597. (Featured in the \textit{Research Highlights} of \textbf{Nature Nanotechnol.}; doi:10.1038/nnano.2006.23). Amdursky, N., Molotskii, M., Gazit, E., and Rosenman, G. (2010) Elementary Building Blocks of Self-Assembled Peptide Nanotubes. \textbf{J. Am. Chem. Soc.} \textit{132}, 15632-1563. (Featured in the \textit{News and Views} of \textbf{Nature} \textit{468}, 516-517). Adler-Abramovich, L., Vaks, L., Carny, O., Trudler, D., Magno, A., Caflisch, A., Frenkel, D. and Gazit, E. (2012) Phenylalanine Assembly into Toxic Fibrils Suggests Amyloid Etiology in Phenylketonuria. \textbf{Nature Chem. Biol.} \textit{8}, 701--706. [Preview Abstract] |
Thursday, March 21, 2013 9:12AM - 9:48AM |
T11.00003: Amyloid at the nanoscale: AFM and single-molecule investigations of early steps of aggregation and mature fibril growth, structure, and mechanics Invited Speaker: Vinod Subramaniam Misfolding and aggregation of proteins into nanometer-scale fibrillar assemblies is a hallmark of many neurodegenerative diseases. We have investigated the self-assembly of the human intrinsically disordered protein alpha-synuclein, involved in Parkinson's disease, into amyloid fibrils. A particularly relevant question is the role of early oligomeric aggregates in modulating the dynamics of protein nucleation and aggregation. We have used single molecule fluorescence spectroscopy to characterize conformational transitions of alpha-synuclein [1], and to gain insights into the structure and composition of oligomeric aggregates of alpha-synuclein [2]. Quantitative atomic force microscopy [3, 4] and nanomechanical investigations [5, 6] provide information on amyloid fibril polymorphism and on nanoscale mechanical properties of mature fibrillar species, while conventional optical and super-resolution imaging have yielded insights into the growth of fibrils and into the assembly of suprafibrillar structures. \\[4pt] [1] Veldhuis, G., I. Segers-Nolten, E. Ferlemann, and V. Subramaniam. 2009. Single-molecule FRET reveals structural heterogeneity of SDS-bound alpha-synuclein. Chembiochem 10:436-439. [2] Zijlstra, N., C. Blum, I. M. Segers-Nolten, M. M. Claessens, and V. Subramaniam. 2012. Molecular Composition of Sub-stoichiometrically Labeled alpha-Synuclein Oligomers Determined by Single-Molecule Photobleaching. Angew Chem Int Ed Engl 51:8821--8824. [3] van Raaij, M. E., I. M. Segers-Nolten, and V. Subramaniam. 2006. Quantitative morphological analysis reveals ultrastructural diversity of amyloid fibrils from alpha-synuclein mutants. Biophys J 91:L96-98. [4] van Raaij, M. E., J. van Gestel, I. M. Segers-Nolten, S. W. de Leeuw, and V. Subramaniam. 2008. Concentration dependence of alpha-synuclein fibril length assessed by quantitative atomic force microscopy and statistical-mechanical theory. Biophys J 95:4871-4878. [5] Sweers, K., K. van der Werf, M. Bennink, and V. Subramaniam. 2011. Nanomechanical properties of alpha-synuclein amyloid fibrils: a comparative study by nanoindentation, harmonic force microscopy, and Peakforce QNM. Nanoscale Res Lett 6:270. [6] Sweers, K. K. M., I. M. J. Segers-Nolten, M. L. Bennink, and V. Subramaniam. 2012. Structural model for $\alpha $-synuclein fibrils derived from high resolution imaging and nanomechanical studies using atomic force microscopy. Soft Matter 8:7215-7222. [Preview Abstract] |
Thursday, March 21, 2013 9:48AM - 10:24AM |
T11.00004: Amyloid Self Assembly Invited Speaker: Tuomas Knowles |
Thursday, March 21, 2013 10:24AM - 11:00AM |
T11.00005: Designing biomaterials exploiting beta-sheet forming peptides self-assembly Invited Speaker: Alberto Saiani The use of non-covalent self-assembly to construct materials has become a prominent strategy in material science offering practical routes for the construction of increasingly functional materials for a variety of applications ranging from electronic to biotechnology. A variety of molecular building blocks can be used for this purpose, one such block that has attracted considerable attention are de-novo designed peptides. The library of 20 natural amino acids offers the ability to play with the intrinsic properties of the peptide such as structure, hydrophobicity, charge and functionality allowing the design of materials with a wide range of properties. The beta-sheet motif is of particular interest as short peptides can be designed to form beta-sheet rich fibres that entangle and consequently form hydrogels. These hydrogels can be further functionalised using specific biological signals or drugs by synthesising functionalised peptides that are incorporated into the hydrogel network during the self-assembling process. This functionalisation approach is very attractive has it does not require any chemistry avoiding therefore the use of additional potentially toxic chemicals. It also offers the possibility to introduce multiple functionalities in a straightforward fashion. The hydrogels can also be made responsive through the use of enzymatic catalysis and/or conjugation with responsive polymers. In this presentation we will discuss the design opportunities offered by these peptides to create new functional biomaterials. [Preview Abstract] |
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