Nanoscale Protein Assemblies from a Circular Permutant of the Tobacco Mosaic Virus

Abstract

The protein coat of the tobacco mosaic virus (TMV) has been explored extensively for the construction of nanoscale architectures. In previous work, we have reported efficient TMV-based light harvesting systems bearing chromophores in a hollow channel of the assembled protein. We have also reported an N-terminal transamination/oximation method that could be used to attach electrodes and catalytic groups to the exterior surface of the rods. To complement these techniques, we report herein a new circular permutant of the TMV capsid protein that repositions the N- and C-termini to the center of the assemblies. This protein can be produced in very high yield through E. coli expression and self-assembles into light harvesting rods that are much like those assembled from the wild-type protein. However, the disks formed from the permutant structure are stable over a significantly wider pH range, greatly improving the practicality of this assembled form for materials applications. The new position of the N-terminus allows functional groups to be installed in the inner pore of the disks, affording geometries reminiscent of natural photosynthetic systems. The permutant also shows the ability to coassemble with regular monomers, allowing the future generation of multicomponent rod structures that are modified on the exterior and interior surfaces, as well as in the internal RNA channel.

Manipulating Excited-State Dynamics of Individual Light-Harvesting Chromophores through Restricted Motions in a Hydrated Nanoscale Protein Cavity

“…48 The cpTMV protein self-assembles into two associated rings, each comprising 17 monomers. These assemblies have a C 2 symmetric double-ring structure with a cavity between the rings (Figure 1b, d) as revealed by X-ray crystallographic analysis.…”

Plant virus directed fabrication of nanoscale materials and devices

“…The ability to control and modify the formation of assembly intermediates represents a powerful means to produce novel ePVN structures that would not form under native conditions. Previous studies have expressed TMV CP and shown that under physiological conditions (neutral pH) these purified CPs form only lower order assemblies that include small aggregates and disks (Bruckman et al, 2011;Dedeo et al, 2010Dedeo et al, , 2011Miller et al, 2007). Recently, a bacterial optimized TMV CP ORF was modified by substituting charge neutralizing amino acids Q and N at position E50 and D77, respectively .…”

“…These findings demonstrate novel strategies through which external stimuli such as nickel ions or redox activity could be used to control TMV ePVN assembly and disassembly. Dedeo et al (2010) took alterations in the TMV PVN surface features to their extreme, utilizing protein design strategies to reposition the N and C terminus of the TMV CP from the outer PVN surface to the inner channel surface. This circular permutant CP was expressed from E. coli and shown to assemble into disks and TMV-like rods upon low pH treatments.…”

“…Using in silico modeling methods Hou et al identified a depression on the surface of the TMV CP permutant that resembled the catalytic site of glutathione peroxidase (GPx), an enzyme involved in oxidative protection (Dedeo et al, 2010;Hou et al, 2012). By creating substitutions at residues 142 (serine to selenocysteine) and 149 (glycine to arginine) within this catalytic site-like depression the authors were able to engineer a functional GPx reaction site on the TMV CP surface.…”

Influence of counter-ions on the self-assembly of ZrO2 nanodisks

“…The hard templates are normally composed of the materials containing well-defined void with the formal of pores and channels, e.g. silica [5], porous alumina [6], and DNA [7][8][9]. In contrast, the relatively flexible soft templates usually consist of surfactants [10], polymers [11,12] and even O 2 bubbles [13].…”