Electrochemical atomic force microscopy imaging of redox-immunomarked proteins on native potyviruses: from subparticle to single-protein resolution.

We show herein that electrochemical atomic force microscopy (AFM-SECM), operated in molecule touching (Mt) mode and combined with redox immunomarking, enables the in situ mapping of the distribution of proteins on individual virus particles and makes localization of individual viral proteins possible. Acquisition of a topography image allows isolated virus particles to be identified and structurally characterized, while simultaneous acquisition of a current image allows the sought after protein, marked by redox antibodies, to be selectively located. We concomitantly show that Mt/AFM-SECM, due to its single-particle resolution, can also uniquely reveal the way redox functionalization endowed to viral particles is distributed both statistically among the viruses and spatially over individual virus particles.

General strategy for ordered noncovalent protein assembly on well-defined nanoscaffolds.

Here we develop a novel approach allowing the noncovalent assembly of proteins on well-defined nanoscaffolds such as virus particles. The antibody-binding peptide Z33 was genetically fused to the monomeric yellow fluorescent protein and 4-coumarate:CoA-ligase 2. This Z33 "tag" allowed their patterning on the surface of zucchini yellow mosaic virus by means of specific antibodies directed against the coat protein of the virus.

Virus scaffolds as enzyme nano-carriers.

The cooperative organization of enzymes by cells is a key feature for the efficiency of living systems. In the field of nanotechnologies, effort currently aims at mimicking this natural organization. Nanoscale resolution and high-registration alignment are necessary to control enzyme distribution in nano-containers or on the surface of solid supports.

A virus-based biocatalyst.

Virus particles are probably the most precisely defined nanometre-sized objects that can be formed by protein self-assembly. Although their natural function is the storage and transport of genetic material, they have more recently been applied as scaffolds for mineralization and as containers for the encapsulation of inorganic compounds. The reproductive power of viruses has been used to develop versatile analytical methods, such as phage display, for the selection and identification of (bio)active compounds.

Optical and EPR spectroscopic studies of demetallation of hemin by L-chain apoferritins.

Earlier crystallographic and spectroscopic studies had shown that horse spleen apoferritin was capable of removing the metal ion from hemin (Fe(III)-protoporphyrin IX) [G. Précigoux, J. Yariv, B.