A DNA-Protein Complex Involved in Bacteriophage ϕX174 Particle Formation

Weisbeek, Peter; Sinsheimer, Robert L.

doi:10.1073/pnas.71.8.3054

Cited by 25 publications

(17 citation statements)

References 15 publications

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“…Either during or subsequent to DNA packaging the procapsid undergoes major structural rearrangements, and the internal scaffolding proteins are removed, generating a 132S particle [18,21,24]. Finally, the external scaffolding is removed, perhaps only upon lysis of the cell [28] ( fig. 2).…”

Section: External Scaffolding Proteinsmentioning

confidence: 99%

Scaffolding proteins and their role in viral assembly

Dokland

1999

Cellular and Molecular Life Sciences (CMLS)

136

139

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Scaffolding proteins are proteins that are required to catalyse, regulate or modulate some step in the assembly of a macromolecular complex. They associate specifically with the nascent protein complex during assembly, but are subsequently removed, and are absent from the mature structure. Scaffolding proteins have been described primarily from viral systems, in particular from the double-stranded DNA bacteriophages, but most likely play a more general role in macromolecular assembly, a fundamental process in all biological systems. Scaffolding proteins may act in a specific fashion, by actively encouraging the formation of correct protein-protein interactions, or more generally by nucleating and promoting assembly. They may also work to ensure the fidelity of the assembly process by preventing the formation of improper interactions, in many ways similar to the role of molecular chaperones in protein folding. In viruses, scaffolding proteins are found both in the form of internal cores and external bracing, and may form elaborate and complex structures. This review will focus on the viral scaffolding proteins, for which an increasing amount of structural and functional information has recently become available.

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Section: External Scaffolding Proteinsmentioning

confidence: 99%

Scaffolding proteins and their role in viral assembly

Dokland

1999

Cellular and Molecular Life Sciences (CMLS)

136

139

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“…In the procapsid, 240 copies of the scaffolding protein D form an external shell, while 60 copies of protein B occupy an internal location (Mukai et al, 1979;Ilag et al, 1995;Dokland et al, 1997). DNA packaging is accompanied by the gain of the DNA-binding protein J (Aoyama et al, 1981) and the loss of the B scaffolding protein (Fujisawa & Hayashi, 1977b), yielding the provirion, or 132 S particle (Weisbeek & Sinsheimer, 1974;Fujisawa & Hayashi, 1977b). Subsequent removal of the external scaffold yields the mature, infectious virion.…”

Section: Introductionmentioning

confidence: 99%

The role of scaffolding proteins in the assembly of the small, single-stranded DNA virus φX174 1 1Edited by I. A. Wilson

Dokland

Bernal

Burch

et al. 1999

Journal of Molecular Biology

123

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“…In the wt G4 extract, both isotopes also sediment at 140S. The sedimenting material is infectious (data not shown) and analogous to the 132S particle of 4X174 (8,17), the penultimate species in the assembly pathway.In the extracts of cells infected with 4XX174 J(Am) or G4 J(Am) mutants (Fig. 1C and D, respectively), no [3H]DNA sediments at 114S, 132S, or 140S.…”

mentioning

confidence: 98%

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confidence: 98%

Functional relationship between the J proteins of bacteriophages phi X174 and G4 during phage morphogenesis

Fane

Head

1992

J Bacteriol

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The functions of the small DNA-binding protein, gpJ, of bacteriophages +X174 and G4 were examined by in vivo cross-complementation and sucrose gradient sedimentation. The morphogenetic roles of the two proteins may differ. The +X174 J protein may be required for the formation or stabilization of the +X174 prohead.Bacteriophages (X174 and G4 are small icosahedral, single-stranded DNA phage of the class Microviridae. Their genomes are of similar length and organization (6,14). Many of their proteins are cross functional (3).The mature virions contain four structural proteins: the major coat protein, gpF; the major spike protein, gpG; the minor spike protein, gpH; and the small DNA-binding protein, gpJ. The least investigated of these four proteins is gpJ, which has been shown to be essential for DNA packaging both in vitro and in vivo (la, 10, 11).The amino sequences of the G4 and PX174 J proteins have been determined (6,14). They are 25 and 38 residues long, respectively. The additional amino acids found in the 4X174 sequence are located in the middle of the protein. The amino termini contain many basic residues. An N-terminal proteolytic fragment of the 4)X174 J protein binds and condenses DNA in vitro (1). The last 13 amino acids are conserved in 11 places. The last seven residues of the PX174 J protein have also been shown to be essential for DNA packaging in vitro (1).In vivo complementation of +X174 J(Am) and G4 J(Am) mutants. To further the in vivo analysis of J-protein function, we assayed the ability of cloned 4X174 and G4 J genes to complement newly constructed J(Am) mutants. The construction of the expression vector carrying the fX174 J gene has been described by Hamatake et al. (11). The J gene from G4 was cloned into the same vector (4). The plasmids will be referred to hereafter as pqXJ and pG4J. G4 and 4X174 J(Am) mutations were generated at the eighth codons of the J genes by oligonucleotide-directed mutagenesis (13).To assay the ability of the cloned J proteins to crosscomplement, the burst sizes of the~X174 J(Am) and G4 J(Am) mutants were measured in cells carrying the plasmids. These results are shown in Table 1.Wild-type (wt) 4~X174 and G4 phage produced large bursts under all conditions. The burst sizes of the (X174J(Am) and G4 J(Am) mutants in cells which do not harbor a plasmid were 3.4 and 0.6 phage per cell, respectively. In the presence of either p4+XJ or pG4J, the G4 J(Am) mutant produced bursts which were significantly higher. The (X174 J(Am) mutant, on the other hand, produced a burst only in the presence of p4XJ. These results indicate that the G4 J protein does not productively contribute to (X174 development, making it unique among the G4 structural proteins. The other three structural proteins have been shown to function during the PX174 life cycle (3). * Corresponding author.The hybrid G4 virions containing 4X174 J protein generated in the above experiment were assayed for heat stability, UV and hydroxylamine sensitivity, and efficiency of adsorption. No differences were observed ...

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A DNA-Protein Complex Involved in Bacteriophage ϕX174 Particle Formation

Cited by 25 publications

References 15 publications

Scaffolding proteins and their role in viral assembly

Scaffolding proteins and their role in viral assembly

The role of scaffolding proteins in the assembly of the small, single-stranded DNA virus φX174 1 1Edited by I. A. Wilson

Functional relationship between the J proteins of bacteriophages phi X174 and G4 during phage morphogenesis

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