Viral capsids: Mechanical characteristics, genome packaging and delivery mechanisms

There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

Abstract.

The main functions of viral capsids are to protect, transport and deliver their genome. The mechanical properties of capsids are supposed to be adapted to these tasks. Bacteriophage capsids also need to withstand the high pressures the DNA is exerting onto it as a result of the DNA packaging and its consequent confinement within the capsid. It is proposed that this pressure helps driving the genome into the host, but other mechanisms also seem to play an important role in ejection. DNA packaging and ejection strategies are obviously dependent on the mechanical properties of the capsid. This review focuses on the mechanical properties of viral capsids in general and the elucidation of the biophysical aspects of genome packaging mechanisms and genome delivery processes of double-stranded DNA bacteriophages in particular.

Related collections

Most cited references 117

Record: found
Abstract: found
Article: not found

Force and velocity measured for single molecules of RNA polymerase.

M Wang, M. J. Schnitzer, H. Yin … (1998)

RNA polymerase (RNAP) moves along DNA while carrying out transcription, acting as a molecular motor. Transcriptional velocities for single molecules of Escherichia coli RNAP were measured as progressively larger forces were applied by a feedback-controlled optical trap. The shapes of RNAP force-velocity curves are distinct from those of the motor enzymes myosin or kinesin, and indicate that biochemical steps limiting transcription rates at low loads do not generate movement. Modeling the data suggests that high loads may halt RNAP by promoting a structural change which moves all or part of the enzyme backwards through a comparatively large distance, corresponding to 5 to 10 base pairs. This contrasts with previous models that assumed force acts directly upon a single-base translocation step.

0 comments Cited 185 times – based on 0 reviews      Review now

Bookmark

Record: found
Abstract: found
Article: not found

Polyamines: mysterious modulators of cellular functions.

K Kashiwagi, K Igarashi (2000)

In recent years the functions of polyamines (putrescine, spermidine, and spermine) have been studied at the molecular level. Polyamines can modulate the functions of RNA, DNA, nucleotide triphosphates, proteins, and other acidic substances. A major part of the cellular functions of polyamines can be explained through a structural change of RNA which occurs at physiological concentrations of Mg(2+) and K(+) because most polyamines exist in a polyamine-RNA complex within cells. Polyamines were found to modulate protein synthesis at several different levels including stimulation of special kinds of protein synthesis, stimulation of the assembly of 30 S ribosomal subunits and stimulation of Ile-tRNA formation. Effects of polyamines on ion channels have also been reported and are gradually being clarified at the molecular level. Copyright 2000 Academic Press.

0 comments Cited 172 times – based on 0 reviews      Review now

Bookmark

Record: found
Abstract: found
Article: not found

INDEPENDENT FUNCTIONS OF VIRAL PROTEIN AND NUCLEIC ACID IN GROWTH OF BACTERIOPHAGE

A. D. Hershey, Martha Chase (1952)

1. Osmotic shock disrupts particles of phage T2 into material containing nearly all the phage sulfur in a form precipitable by antiphage serum, and capable of specific adsorption to bacteria. It releases into solution nearly all the phage DNA in a form not precipitable by antiserum and not adsorbable to bacteria. The sulfur-containing protein of the phage particle evidently makes up a membrane that protects the phage DNA from DNase, comprises the sole or principal antigenic material, and is responsible for attachment of the virus to bacteria. 2. Adsorption of T2 to heat-killed bacteria, and heating or alternate freezing and thawing of infected cells, sensitize the DNA of the adsorbed phage to DNase. These treatments have little or no sensitizing effect on unadsorbed phage. Neither heating nor freezing and thawing releases the phage DNA from infected cells, although other cell constituents can be extracted by these methods. These facts suggest that the phage DNA forms part of an organized intracellular structure throughout the period of phage growth. 3. Adsorption of phage T2 to bacterial debris causes part of the phage DNA to appear in solution, leaving the phage sulfur attached to the debris. Another part of the phage DNA, corresponding roughly to the remaining half of the DNA of the inactivated phage, remains attached to the debris but can be separated from it by DNase. Phage T4 behaves similarly, although the two phages can be shown to attach to different combining sites. The inactivation of phage by bacterial debris is evidently accompanied by the rupture of the viral membrane. 4. Suspensions of infected cells agitated in a Waring blendor release 75 per cent of the phage sulfur and only 15 per cent of the phage phosphorus to the solution as a result of the applied shearing force. The cells remain capable of yielding phage progeny. 5. The facts stated show that most of the phage sulfur remains at the cell surface and most of the phage DNA enters the cell on infection. Whether sulfur-free material other than DNA enters the cell has not been determined. The properties of the sulfur-containing residue identify it as essentially unchanged membranes of the phage particles. All types of evidence show that the passage of phage DNA into the cell occurs in non-nutrient medium under conditions in which other known steps in viral growth do not occur. 6. The phage progeny yielded by bacteria infected with phage labeled with radioactive sulfur contain less than 1 per cent of the parental radioactivity. The progeny of phage particles labeled with radioactive phosphorus contain 30 per cent or more of the parental phosphorus. 7. Phage inactivated by dilute formaldehyde is capable of adsorbing to bacteria, but does not release its DNA to the cell. This shows that the interaction between phage and bacterium resulting in release of the phage DNA from its protective membrane depends on labile components of the phage particle. By contrast, the components of the bacterium essential to this interaction are remarkably stable. The nature of the interaction is otherwise unknown. 8. The sulfur-containing protein of resting phage particles is confined to a protective coat that is responsible for the adsorption to bacteria, and functions as an instrument for the injection of the phage DNA into the cell. This protein probably has no function in the growth of intracellular phage. The DNA has some function. Further chemical inferences should not be drawn from the experiments presented.

0 comments Cited 164 times – based on 0 reviews      Review now

Bookmark

All references

Author and article information

Contributors

: +31 20 5987991 , gwuite@nat.vu.nl

Journal

Journal ID (nlm-ta): Cell Mol Life Sci

Title: Cellular and Molecular Life Sciences

Publisher: Birkhäuser-Verlag (Basel )

ISSN (Print): 1420-682X

ISSN (Electronic): 1420-9071

Publication date (Electronic): 19 March 2007

Publication date (Print): June 2007

Volume: 64

Issue: 12

Pages: 1484-1497

Affiliations

[1 ]Fysica van complexe systemen, Vrije Universiteit, 1081 HV Amsterdam, The Netherlands

[2 ]Department of Biochemistry, Centre for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, 221 00 Lund, Sweden

Article

Publisher ID: 6451

DOI: 10.1007/s00018-007-6451-1

PMC ID: 2771126

PubMed ID: 17440680

SO-VID: 39a15fc0-9348-484a-a6fb-645cc8365a67

History

Custom metadata

ScienceOpen disciplines: Molecular biology

Keywords: capsid mechanics,genome packaging,atomic force microscopy,osmotic pressure,genome delivery,optical tweezers,biophysics

Data availability:

ScienceOpen disciplines: Molecular biology

Keywords: capsid mechanics, genome packaging, atomic force microscopy, osmotic pressure, genome delivery, optical tweezers, biophysics

Comments

Comment on this article

scite_

Smart Citations

Citing PublicationsSupportingMentioningContrasting

View Citations

See how this article has been cited at scite.ai

scite shows how a scientific paper has been cited by providing the context of the citation, a classification describing whether it supports, mentions, or contrasts the cited claim, and a label indicating in which section the citation was made.