title: Discrete fracture patterns of virus shells reveal mechanical building blocks.
abstract: Viral shells are self-assembled protein nanocontainers with remarkable material properties. They combine simplicity of construction with toughness and complex functionality. These properties make them interesting for bionanotechnology. To date we know little about how virus structure determines assembly pathways and shell mechanics. We have here used atomic force microscopy to study structural failure of the shells of the bacteriophage Φ29. We observed rigidity patterns following the symmetry of the capsid proteins. Under prolonged force exertion, we observed fracture along well-defined lines of the 2D crystal lattice. The mechanically most stable building block of the shells was a trimer. Our approach of "reverse engineering" the virus shells thus made it possible to identify stable structural intermediates. Such stable intermediates point to a hierarchy of interactions among equal building blocks correlated with distinct next-neighbor interactions. The results also demonstrate that concepts from macroscopic materials science, such as fracture, can be usefully employed in molecular engineering.
authors.affiliation: Faculty of Exact Sciences, Department of Physics and Astronomy, Vrije Universiteit, De Boeleaan 1081, 1081 HV Amsterdam, The Netherlands.
authors.forename: Irena L
authors.initials: IL
authors.lastname: Ivanovska
authors.forename: Roberto
authors.initials: R
authors.lastname: Miranda
authors.forename: Jose L
authors.initials: JL
authors.lastname: Carrascosa
authors.forename: Gijs J L
authors.initials: GJ
authors.lastname: Wuite
authors.forename: Christoph F
authors.initials: CF
authors.lastname: Schmidt
mesh_terms: D017103:Bacillus Phages / Q000737:chemistry* / Q000648:ultrastructure; D001412:Bacillus subtilis / Q000821:virology; D002213:Capsid / Q000737:chemistry* / Q000648:ultrastructure; D036022:Capsid Proteins / Q000032:analysis* / Q000737:chemistry; D020285:Cryoelectron Microscopy; D003460:Crystallization; D018625:Microscopy, Atomic Force / Q000379:methods*; D008958:Models, Molecular; D055503:Protein Multimerization
chemical_list: D036022:Capsid Proteins