Bacteriophage φW-14: The contribution of covalently bound putrescine to DNA Packing in the Phage Head

Scraba, Douglas G.; Bradley, R.; Leyritz-Wills, M.; Warren, R. A. J.

doi:10.1016/0042-6822(83)90298-2

Cited by 27 publications

(27 citation statements)

References 23 publications

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“…precA (23,ug/mL) was incubated with DNA (2.5,ug/mL) in a buffer consisting of 10 mM Mg(OAc)2, 0.6 mM ATPyS and 20 mM sodium 2 0 cacodylate (pH 6.5) for 4 hrs at 22 C. Samples were adsorbed to glow-discharge-treated carbon films, washed with 5 mM Mg(OAc)2 and stained with 2% uranyl acetate. precA plus (a) calf thymus DNA; (b) calf thymus DNA pre-treated with anthramycin (Materials and Methods); (c) linear PM2 DNA; (d) linear PM2 DNA pre-treated with anthramycin (see b); (e) T4 DNA; (f) DNA from the Pseudomonas acidivorans phage, 0W-14 (29).…”

Section: Resultsmentioning

confidence: 99%

Studies of the interaction of RecA protein with DNA

et al. 1983

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Ethidium fluorescence assays were adapted for the rapid and sensitive detection of precA; in addition, fluorescence measurements on binding precA to linear, OC and CCC PM2 DNAs have enabled the stoichiometry of precA binding as well as the precA-induced unwinding angle of DNA to be determined. The stoichiometry of binding was independently confirmed by sedimentation analysis to be one precA molecule per 3 bp. The unwinding angle was also independently confirmed by measurements of fluorescence changes induced by the binding of precA to CCC DNA which was relaxed by topoisomerase to give a precA-induced unwinding angle of 51 degrees. Electron microscopy of OC DNA molecules which bound nonsaturating amounts of precA revealed that the length increase in DNA due to precA was approximately 55%. Finally, examination of negatively stained precA complexes with a variety of linear DNAs showed that the minor groove is the primary site of interaction for this protein.

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Section: Resultsmentioning

confidence: 99%

Studies of the interaction of RecA protein with DNA

et al. 1983

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“…In these giant phages, the DNA is clearly oriented parallel to the extended long axis of the giant capsids that can be more than tenfold longer than wild-type T4, while maintaining the same width as normal capsids. However, a phage with the unusual highly positively charged base α-putrescinylthymine packages DNA to ~630 mg/ml, except when this modification is removed, showing that the DNA structure and charge critically determine packaging density (Scraba et al 1983). Phages with unique sequence ends such as lambda significantly under-package deletion containing genomes of ~75% normal length to yield active phages with looser than 2.5-nm of duplex-to-duplex overall spacing.…”

Section: 2 Naked Dna Condensate Structure In Phage Capsidsmentioning

confidence: 99%

Condensed Genome Structure

Black

Thomas

2011

Viral Molecular Machines

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Large, tailed dsDNA-containing bacteriophage genomes are packaged to a conserved and high density (~500 mg/ml), generally in ~2.5-nm, duplex-to-duplex, spaced, organized DNA shells within icosahedral capsids. Phages with these condensate properties, however, differ markedly in their inner capsid structures: (1) those with a naked condensed DNA, (2) those with many dispersed unstructured proteins embedded within the DNA, (3) those with a small number of localized proteins, and (4) those with a reduced or DNA-free internal protein structure of substantial volume. The DNA is translocated and condensed by a high-force ATPase motor into a procapsid already containing the proteins that are to be ejected together with the DNA into the infected host. The condensed genome structure of a single-phage type is unlikely to be precisely determined and can change without loss of function to fit an altered capsid size or internal structure. Although no such single-phage condensed genome structure is known exactly, it is known that a single general structure is unlikely to apply to all such phages.

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“…Nevertheless, the fact that most dsDNA phages have similar densities of packaged DNA suggests that this feature is important in phage biology. Virions of Pseudomonas acidovorans øW-14 (morphologically related to T4) contain a genome packaged at sim;30% higher density, dependent on DNA containing the polyamine-modified base α-putrescinylthymine (putThy) [26]. About 25% of the DNAphosphate charges can be neutralized by the putThy, and some neutralization is necessary because mutants partially defective in putThy synthesis package sim;11% less DNA than wildtype into virions.…”

Section: Pressure In the Mature Phage Particlementioning

confidence: 99%

Is phage DNA ‘injected’ into cells—biologists and physicists can agree

Grayson

Molineux

2007

Current Opinion in Microbiology

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The double-stranded DNA inside bacteriophages is packaged at a density of approximately 500 mg/ml and exerts an osmotic pressure of tens of atmospheres. This pressure is commonly assumed to cause genome ejection during infection. Indeed, by the addition of their natural receptors, some phages can be induced in vitro to completely expel their genome from the virion. However, the osmotic pressure of the bacterial cytoplasm exerts an opposing force, making it impossible for the pressure of packaged DNA to cause complete genome ejection in vivo. Various processes for complete genome ejection are discussed, but we focus on a novel proposal suggesting that the osmotic gradient between the extracellular environment and the cytoplasm results in fluid flow through the phage virion at the initiation of infection. The phage genome is thereby sucked into the cell by hydrodynamic drag.

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Bacteriophage φW-14: The contribution of covalently bound putrescine to DNA Packing in the Phage Head

Cited by 27 publications

References 23 publications

Studies of the interaction of RecA protein with DNA

Studies of the interaction of RecA protein with DNA

Condensed Genome Structure

Is phage DNA ‘injected’ into cells—biologists and physicists can agree

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