Understanding amyloid aggregation by statistical analysis of atomic force microscopy images.

The aggregation of proteins is central to many aspects of daily life, including food processing, blood coagulation, eye cataract formation disease and prion-related neurodegenerative infections. However, the physical mechanisms responsible for amyloidosis-the irreversible fibril formation of various proteins that is linked to disorders such as Alzheimer's, Creutzfeldt-Jakob and Huntington's diseases-have not yet been fully elucidated. Here, we show that different stages of amyloid aggregation can be examined by performing a statistical polymer physics analysis of single-molecule atomic force microscopy images of heat-denatured beta-lactoglobulin fibrils. The atomic force microscopy analysis, supported by theoretical arguments, reveals that the fibrils have a multistranded helical shape with twisted ribbon-like structures. Our results also indicate a possible general model for amyloid fibril assembly and illustrate the potential of this approach for investigating fibrillar systems.

[1]  A. N. Semenov,et al.  Hierarchical self-assembly of chiral rod-like molecules as a model for peptide β-sheet tapes, ribbons, fibrils, and fibers , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[2]  J. Gerrard,et al.  Formation of amyloid-like fibrils by ovalbumin and related proteins under conditions relevant to food processing. , 2007, Journal of agricultural and food chemistry.

[3]  Walraj S. Gosal,et al.  Fibrillar beta-lactoglobulin gels: Part 1. Fibril formation and structure. , 2004, Biomacromolecules.

[4]  L. Sagis,et al.  Mesoscopic properties of semiflexible amyloid fibrils. , 2004, Langmuir : the ACS journal of surfaces and colloids.

[5]  M. R. Nilsson.  Techniques to study amyloid fibril formation in vitro. , 2004, Methods.

[6]  P. Graumann.  Cytoskeletal elements in bacteria. , 2004, Current opinion in microbiology.

[7]  Fabrizio Chiti,et al.  Amyloid formation by globular proteins under native conditions. , 2009, Nature chemical biology.

[8]  R. Mezzenga,et al.  Liquid crystalline phase behavior of protein fibers in water: experiments versus theory. , 2010, Langmuir : the ACS journal of surfaces and colloids.

[9]  C. Dobson.  Protein folding and misfolding , 2003, Nature.

[10]  Richard D. Leapman,et al.  Molecular structural basis for polymorphism in Alzheimer's β-amyloid fibrils , 2008, Proceedings of the National Academy of Sciences.

[11]  Frédéric Cardinaux,et al.  Equilibrium cluster formation in concentrated protein solutions and colloids , 2004, Nature.

[12]  H. Lashuel,et al.  Molecular electron microscopy approaches to elucidating the mechanisms of protein fibrillogenesis. , 2005, Methods in molecular biology.

[13]  P. Lansbury,et al.  Protofibrils, pores, fibrils, and neurodegeneration: separating the responsible protein aggregates from the innocent bystanders. , 2003, Annual review of neuroscience.

[14]  Knut Einar Larsen.  Part 3 , 2001, Dimensions of Mystical Experiences.

[15]  Erik van der Linden,et al.  Effect of stirring and seeding on whey protein fibril formation. , 2007, Journal of agricultural and food chemistry.

[16]  P. Pudney,et al.  Novel Amyloid Fibrillar Networks Derived from a Globular Protein: β-Lactoglobulin† , 2002 .

[17]  Walraj S. Gosal,et al.  Fibrillar β-Lactoglobulin Gels: Part 1. Fibril Formation and Structure , 2004 .

[18]  K. Rechendorff,et al.  Conformation of circular DNA in two dimensions. , 2008, Physical review letters.

[19]  Z. Tomori,et al.  Interactive measurement and characterization of DNA molecules by analysis of AFM images , 2005, Cytometry. Part A : the journal of the International Society for Analytical Cytology.

[20]  A. Clark,et al.  Heat-induced gelation of globular proteins: part 3. Molecular studies on low pH beta-lactoglobulin gels. , 2000, International journal of biological macromolecules.

[21]  Robert A. Grothe,et al.  Structure of the cross-beta spine of amyloid-like fibrils. , 2005, Nature.

[22]  Jin-Mi Jung,et al.  Structure of heat-induced beta-lactoglobulin aggregates and their complexes with sodium-dodecyl sulfate. , 2008, Biomacromolecules.

[23]  H. Kueh,et al.  Structural Plasticity in Actin and Tubulin Polymer Dynamics , 2009, Science.

[24]  R. Mezzenga,et al.  Understanding foods as soft materials , 2005, Nature materials.

[25]  R. de Vries,et al.  Strong impact of ionic strength on the kinetics of fibrilar aggregation of bovine beta-lactoglobulin. , 2006, Biomacromolecules.

[26]  H. Hakimzadeh,et al.  Part 1 , 2011 .

[27]  Michele Vendruscolo,et al.  Role of Intermolecular Forces in Defining Material Properties of Protein Nanofibrils , 2007, Science.

[28]  C M Dobson,et al.  Ultrastructural organization of amyloid fibrils by atomic force microscopy. , 2000, Biophysical journal.

[29]  R. de Vries,et al.  Multiple steps during the formation of beta-lactoglobulin fibrils. , 2003, Biomacromolecules.

[30]  L. Regan,et al.  A general model for amyloid fibril assembly based on morphological studies using atomic force microscopy. , 2003, Biophysical journal.

[31]  V. Morris,et al.  Fine-stranded and particulate aggregates of heat-denatured whey proteins visualized by atomic force microscopy. , 2002, Biomacromolecules.

[32]  D. Selkoe.  Folding proteins in fatal ways , 2003, Nature.

[33]  A. Donald,et al.  Aggregation across the length-scales in β-lactoglobulin , 2005 .

[34]  C. Dobson,et al.  Protein misfolding, functional amyloid, and human disease. , 2006, Annual review of biochemistry.

[35]  L. Sagis,et al.  Effect of electrostatic interactions on the percolation concentration of fibrillar beta-lactoglobulin gels. , 2002, Biomacromolecules.

[36]  Manning.  Correlation of polymer persistence length with Euler buckling fluctuations. , 1986, Physical review. A, General physics.