The assembly in vitro of some small spherical viruses, hybrid viruses, and other nucleoproteins

Hiebert, E.; Bancroft, J.B.; Bracker, Charles E.

doi:10.1016/0042-6822(68)90069-x

Cited by 141 publications

(68 citation statements)

References 30 publications

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“…It will be shown that changing the polyelectrolyte from a linear chain to a multiarmed star (which considerably reduces its physical dimension, one of the main effects of the secondary struc- *This Direct Submission article had a prearranged editor. 1 To whom correspondence should be addressed. E-mail: zgw@caltech.edu.…”

Section: Clarification Of the Optimal Genome Lengthmentioning

confidence: 99%

“…In a series of classic experiments, Bancroft and coworkers (1,2) demonstrated that certain viruses can encapsidate nonnative RNA and even generic polyanions. Dominance of the electrostatics as the driving force for viral assembly has led to the expectation of a simple relationship between the total capsid charge Q P and the genome charge Q R , as every nucleotide carries one unit of negative charge.…”

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confidence: 99%

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Thermodynamic basis for the genome to capsid charge relationship in viral encapsidation

Ting

Wang

2011

Proc. Natl. Acad. Sci. U.S.A.

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We establish an appropriate thermodynamic framework for determining the optimal genome length in electrostatically driven viral encapsidation. Importantly, our analysis includes the electrostatic potential due to the Donnan equilibrium, which arises from the semipermeable nature of the viral capsid, i.e., permeable to small mobile ions but impermeable to charged macromolecules. Because most macromolecules in the cellular milieu are negatively charged, the Donnan potential provides an additional driving force for genome encapsidation. In contrast to previous theoretical studies, we find that the optimal genome length is the result of combined effects from the electrostatic interactions of all charged species, the excluded volume and, to a very significant degree, the Donnan potential. In particular, the Donnan potential is essential for obtaining negatively overcharged viruses. The prevalence of overcharged viruses in nature may suggest an evolutionary preference for viruses to increase the amount of genome packaged by utilizing the Donnan potential (through increases in the capsid radius), rather than high charges on the capsid, so that structural stability of the capsid is maintained.polyelectrolyte | viral assembly T he most prevalent viruses in nature are single-stranded RNA viruses with the genetic material enclosed in icosahedral-shaped capsids made up of 60 T protein units, where the T-number is a small integer index. The protein units (capsomers) often contain highly basic peptide arms that extend into the capsid interior and, under physiological conditions, are positively charged. Electrostatic attraction provides the driving force for encapsidating the negatively charged RNA, which, in turn, helps overcome the electrostatic repulsion among the capsomers during the capsid assembly.In a series of classic experiments, Bancroft and coworkers (1, 2) demonstrated that certain viruses can encapsidate nonnative RNA and even generic polyanions. Dominance of the electrostatics as the driving force for viral assembly has led to the expectation of a simple relationship between the total capsid charge Q P and the genome charge Q R , as every nucleotide carries one unit of negative charge. Belyi and Muthukumar (3) compiled data for 19 wild type viruses from several viral families and found an apparent "universal" charge ratio of Q R ∕Q P ≈ 1.6, which they explained by combining the ground-state dominance approximation for polyelectrolyte binding to an oppositely charged polymer brush with the Manning condensation theory (4). The former predicts a 1∶1 charge ratio and the latter is used as a qualitative argument for the actual charge on the RNA being less than the nominal charge. Hu, et al. (5), however, assumed that the RNA winds around individual peptide arms and found that the viruses are most stable when the total contour length of the RNA is close to the total length of the peptide arms; this roughly gives a charge ratio of 2. In other works that ignore the peptide arms completely, there is additional disagreemen...

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Section: Clarification Of the Optimal Genome Lengthmentioning

confidence: 99%

mentioning

confidence: 99%

Thermodynamic basis for the genome to capsid charge relationship in viral encapsidation

Ting

Wang

2011

Proc. Natl. Acad. Sci. U.S.A.

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“…BMV and CCMV have different densities, largely due to the different compositions of their coat proteins, and density patterns. The latter are probably a result of slightly different molecular weights of the sums of the jointly encapsidated 3 + 4 RNA species relative to the molecular weights of the separately encapsidated r and a species which comprise the heavy and light bands in CsC1 (details of density-distribution considerations, which obviate the necessity of the monomer-tetramer theory (Bancroft et al 1968), will be published separately). This difference in relative densities results in CCMV having a clear central component whereas BMV seems to lack one (Fig.…”

Section: Short Communicationsmentioning

confidence: 99%

A Virus Made from Parts of the Genomes of Brome Mosaic and Cowpea Chlorotic Mottle Viruses

Bancroft

1972

Journal of General Virology

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“…This includes rod-like viruses such as tobacco mosaic virus TMV [3,4], the first virus reconstituted in vitro, and spherical viruses such as cowpea chlorotic mottle virus CCMV [8], the first spherical virus reassembled in vitro form its constituents. In fact, under the right conditions, virus coat proteins quite readily encapsulate the RNA of other viruses and even synthetic polyanions and charged nanoparticles [7][8][9][12][13][14][15]. Interestingly, the purified capsid proteins of human immunodeficiency virus (HIV) also spontaneously assemble around the RNA of the virus, but in this case the formed capsids have a conical structure [16][17][18][19][21][22][23][24].…”

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Impact of the topology of viral RNAs on their encapsulation by virus coat proteins

Schoot

Zandi

2013

J Biol Phys

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Single-stranded RNAs of simple viruses seem to be topologically more compact than other types of single-stranded RNA. It has been suggested that this has an evolutionary purpose: more compact structures are more easily encapsulated in the limited space that the cavity of the virus capsid offers. We employ a simple Flory theory to calculate the optimal amount of polymers confined in a viral shell. We find that the free energy gain or more specifically the efficiency of RNA encapsidation increases substantially with topological compactness. We also find that the optimal length of RNA encapsidated in a capsid increases with the degree of branching of the genome even though this effect is very weak. Further, we show that if the structure of the branching of the polymer is allowed to anneal, the optimal loading increases substantially.

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The assembly in vitro of some small spherical viruses, hybrid viruses, and other nucleoproteins

Cited by 141 publications

References 30 publications

Thermodynamic basis for the genome to capsid charge relationship in viral encapsidation

Thermodynamic basis for the genome to capsid charge relationship in viral encapsidation

A Virus Made from Parts of the Genomes of Brome Mosaic and Cowpea Chlorotic Mottle Viruses

Impact of the topology of viral RNAs on their encapsulation by virus coat proteins

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