Structures of the native and swollen forms of cowpea chlorotic mottle virus determined by X-ray crystallography and cryo-electron microscopy

Speir, Jeffrey A.; Munshi, Sanjeev; Wang, Guoji; Baker, Timothy S.; Johnson, John E.

doi:10.1016/s0969-2126(01)00135-6

Cited by 658 publications

(791 citation statements)

References 55 publications

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“…In contrast, most of the basic residues are near the amino terminus and project into the capsid interior. 21 A simple calculation of the pH dependence of the charge on a CCMV capsid on the pH from the pK a values of the isolated residues in which the contribution of the basic (largely interior) lysine and arginine residues is omitted -gives an isoelectric point of 3.6, which is essentially identical to that of CCMV. Moreover, as shown in Figure 12, the shape of the curve is closely similar to the measured electrophoretic mobility.…”

Section: Discussionmentioning

confidence: 99%

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Phase Diagram of Self-assembled Viral Capsid Protein Polymorphs

et al. 2009

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We present an experimental study of the self-assembly of capsid proteins of the cowpea chlorotic mosaic virus (CCMV), in the absence of the viral genome, as a function of pH and ionic strength. In accord with previous measurements, a wide range of polymorphs can be identified by electron microscopy, among them single and multiwalled shells and tubes. The images are analyzed with respect to size and shape of aggregates, and evidence is given that equilibrium has been achieved, allowing a phase diagram to be constructed. Some previously unreported structures are also described. The range and stability of the polymorphs can be understood in terms of electrostatic interactions and the way they affect the spontaneous curvature of protein networks and the relative stabilities of pentamers and hexamers.

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Section: Discussionmentioning

confidence: 99%

“…It is known 21 that the diameter of CCMV capsids does not change until the pH is close to 7, at which point the capsid diameter expands by 10%. Thus, the interprotein interactions are not affected in the range of pH at which multishells are stable.…”

Section: Discussionmentioning

confidence: 99%

Phase Diagram of Self-assembled Viral Capsid Protein Polymorphs

et al. 2009

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“…[18][19][20] The differential Poisson equation describes the electrostatic potential Φ(r) in a medium with a dielectric scalar field ε(r) and with a charge density ρ(r) (1) In a solvated molecular system, the charge density is divided into the fixed interior charge distribution of the molecule, ρ int (r), and a mobile exterior charge density of the solvent and ions. The exterior is modeled as a dielectric continuum with the mobile ion density approximated by a Boltzmann distribution at temperature T. Equation 1, therefore, takes the form of a nonlinear Poisson-Boltzmann (PB) equation (2) where ε(r) is the dielectric constant of the solute or the solvent, k is the Boltzmann constant, λ equals 1 for ion-accessible regions and 0 elsewhere. The is the modified Debye-Hückel parameter defined as (3) where N A is the Avogadro constant, e the charge of an electron, and I the ionic strength.…”

Section: Theorymentioning

confidence: 99%

Electrostatic properties of cowpea chlorotic mottle virus and cucumber mosaic virus capsids

et al. 2005

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Electrostatic properties of cowpea chlorotic mottle virus (CCMV) and cucumber mosaic virus (CMV) were investigated using numerical solutions to the Poisson-Boltzmann equation. Experimentally, it has been shown that CCMV particles swell in the absence of divalent cations when the pH is raised from 5 to 7. CMV, although structurally homologous, does not undergo this transition. An analysis of the calculated electrostatic potential confirms that a strong electrostatic repulsion at the calcium binding sites in the CCMV capsid is most likely the driving force for the capsid swelling process during the release of calcium. The binding interaction between the encapsulated genome material (RNA) inside of the capsid and the inner capsid shell is weakened during the swelling transition. This probably aids in the RNA release process, but it is unlikely that the RNA is released through capsid openings due to unfavorable electrostatic interaction between the RNA and capsid inner shell residues at these openings. Calculations of the calcium binding energies show that Ca 2+ can bind both to the native and swollen forms of the CCMV virion. Favorable binding to the swollen form suggests that Ca 2+ ions can induce the capsid contraction and stabilize the native form.

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“…The virus is composed of 180 identical coat protein subunits, which encapsulate the viral RNA (ref. 22). An interesting feature of the CCMV virus is its pH-dependent gating behaviour 23 .…”

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confidence: 99%

“…The pore size of the intact virus is known to depend on the pH (ref. 22). At pH 5, the Figure 3 Enzyme activity in the presence of single capsids.…”

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confidence: 99%