Refined Atomic Model of the Four-Layer Aggregate of the Tobacco Mosaic Virus Coat Protein at 2.4-Å Resolution

Abstract

Previous x-ray studies (2.8-A resolution) on crystals of tobacco mosaic virus coat protein grown from solutions containing high salt have characterized the structure of the protein aggregate as a dimer of a bilayered cylindrical disk formed by 34 chemically identical subunits. We have determined the crystal structure of the disk aggregate at 2.4-A resolution using x-ray diffraction from crystals maintained at cryogenic temperatures. Two regions of interest have been extensively refined. First, residues of the low-radius loop region, which were not modeled previously, have been traced completely in our electron density maps. Similar to the structure observed in the virus, the right radial helix in each protomer ends around residue 87, after which the protein chain forms an extended chain that extends to the left radial helix. The left radial helix appears as a long alpha-helix with high temperature factors for the main-chain atoms in the inner portion. The side-chain atoms in this region (residues 90-110) are not visible in the electron density maps and are assumed to be disordered. Second, interactions between subunits in the symmetry-related central A pair have been determined. No direct protein-protein interactions are observed in the major overlap region between these subunits; all interactions are mediated by two layers of ordered solvent molecules. The current structure emphasizes the importance of water in biological macromolecular assemblies.

Structure–function relationship between the tobamovirus TMV-Cg coat protein and the HR-like response

“…As observed in Fig. 6, the highest atomic fluctuations (.0.2 nm) occur in the inner surface loop from residues 90 to 110 in agreement with the high temperature factors observed for the analogous region in crystallographic structures of TMV-U1 (Namba & Stubbs 1986;Bhyravbhatla et al, 1998). Substantial fluctuations were also observed in the N-and C-terminal regions, again consistent with these crystallographic diffraction reports.…”

High-resolution Electron Microscopy of Helical Specimens: A Fresh Look at Tobacco Mosaic Virus

“…The so-called protein disk form was crystallized and resolved to atomic detail in 1978 and refined in 1998. 16,17 The structure of the helical form of the virus has been investigated for several decades using electron microscopy 18 and X-ray fiber diffraction. 19 The fiber diffraction study led to a structure of 2.9 Å resolution and an atomic model for the helical form.…”

Probing nanomechanical properties from biomolecules to living cells

“…The tobacco mosaic virus has been well characterized [6]. At a low level of resolution, it has a rod-like shape, which renders theoretical calculations of its mechanical properties, such as the elastic modulus, relatively easy.…”

“…However, owing to the hierarchical structure of collagen, it has been difficult to pinpoint the relative contributions of different organizational levels to the mechanical behavior of the polymer as a whole. This circumstance accounts for the broad range of reported values for Young's modulus (1)(2)(3)(4)(5)(6)(7)(8). In an attempt to streamline the system, Yang et al [101] deposited unfixed and glutaraldehyde-fixed collagen fibers upon a microfabricated substrate and made AFM indentation measurements on the suspended fragment.…”