Structure and assembly of filamentous bacterial viruses

1976 ◽  
Vol 276 (943) ◽  
pp. 81-98 ◽  
Keyword(s):  
Plasma Membrane ◽  
Coat Protein ◽  
Axial Direction ◽  
Early Step ◽  
Circular Dna ◽  
Protein Subunits ◽  
Myosin Filaments ◽  
Bacterial Viruses ◽  
Α Helix ◽  
Protein Shell

Filamentous bacterial viruses are flexible nucleoprotein rods, about 6 nm in diameter by 1000-2000 nm in length (depending on the virus strain). A protein shell encloses a central core of single-stranded circular DNA. The coat protein subunits forming the shell are largely α-helix, elongated in an axial direction, and also sloping radially, so as to overlap each other and give an arrangement of subunits reminiscent of scales on a fish. This arrangement of α-helices is rather like some models of myosin filaments. An early step in assembly of the virion is the formation of a complex between the viral DNA and an intracellular packaging protein that is not found in completed virions. Newly synthesized coat protein becomes associated with the plasma membrane of the cell. During the final steps of assembly, the packaging protein is displaced from the DNA and replaced by coat protein as the virion passes out through the plasma membrane of the host cell.

scholarly journals Structure of a headful DNA-packaging bacterial virus at 2.9 Å resolution by electron cryo-microscopy

2017 ◽  
Vol 114 (14) ◽  
pp. 3601-3606 ◽  
Author(s):  
Haiyan Zhao ◽  
Kunpeng Li ◽  
Anna Y. Lynn ◽  
Keith E. Aron ◽  
Guimei Yu ◽  
...  
Keyword(s):  
Self Assembly ◽  
Noncovalent Interactions ◽  
Dna Packaging ◽  
Protein Subunits ◽  
Significant Strength ◽  
Phage Dna ◽  
Mortise And Tenon ◽  
Α Helix ◽  
Β Sheet ◽  
Protein Shell

The enormous prevalence of tailed DNA bacteriophages on this planet is enabled by highly efficient self-assembly of hundreds of protein subunits into highly stable capsids. These capsids can stand with an internal pressure as high as ∼50 atmospheres as a result of the phage DNA-packaging process. Here we report the complete atomic model of the headful DNA-packaging bacteriophage Sf6 at 2.9 Å resolution determined by electron cryo-microscopy. The structure reveals the DNA-inflated, tensed state of a robust protein shell assembled via noncovalent interactions. Remarkable global conformational polymorphism of capsid proteins, a network formed by extended N arms, mortise-and-tenon–like intercapsomer joints, and abundant β-sheet–like mainchain:mainchain intermolecular interactions, confers significant strength yet also flexibility required for capsid assembly and DNA packaging. Differential formations of the hexon and penton are mediated by a drastic α–helix-to-β–strand structural transition. The assembly scheme revealed here may be common among tailed DNA phages and herpesviruses.

Head Size and DNA Content in Bacteriophage T4

1972 ◽  
Vol 30 ◽  
pp. 200-201
Author(s):  
Fred Eiserling ◽  
A. H. Doermann ◽  
Linde Boehner
Keyword(s):  
Electron Microscopy ◽  
Dna Content ◽  
Bacteriophage T4 ◽  
Head Size ◽  
Virus Particles ◽  
Altered Protein ◽  
A Cell ◽  
Bacterial Viruses ◽  
A Site ◽  
Protein Shell

The control of form or shape inheritance can be approached by studying the morphogenesis of bacterial viruses. Shape variants of bacteriophage T4 with altered protein shell (capsid) size and nucleic acid (DNA) content have been found by electron microscopy, and a mutant (E920g in gene 66) controlling head size has been described. This mutant produces short-headed particles which contain 2/3 the normal DNA content and which are non-viable when only one particle infects a cell (Fig. 1).We report here the isolation of a new mutant (191c) which also appears to be in gene 66 but at a site distinct from E920g. The most striking phenotype of the mutant is the production of about 10% of the phage yield as “giant” virus particles, from 3 to 8 times longer than normal phage (Fig. 2).

scholarly journals Role of the Endocytic Machinery in the Sorting of Lysosome-associated Membrane Proteins

2005 ◽  
Vol 16 (9) ◽  
pp. 4231-4242 ◽  
Author(s):  
Katy Janvier ◽  
Juan S. Bonifacino
Keyword(s):  
Plasma Membrane ◽  
Coat Protein ◽  
Membrane Proteins ◽  
Adaptor Protein ◽  
The Other ◽  
Sorting Signals ◽  
Efficient Delivery ◽  
Endocytic Machinery

The limiting membrane of the lysosome contains a group of transmembrane glycoproteins named lysosome-associated membrane proteins (Lamps). These proteins are targeted to lysosomes by virtue of tyrosine-based sorting signals in their cytosolic tails. Four adaptor protein (AP) complexes, AP-1, AP-2, AP-3, and AP-4, interact with such signals and are therefore candidates for mediating sorting of the Lamps to lysosomes. However, the role of these complexes and of the coat protein, clathrin, in sorting of the Lamps in vivo has either not been addressed or remains controversial. We have used RNA interference to show that AP-2 and clathrin—and to a lesser extent the other AP complexes—are required for efficient delivery of the Lamps to lysosomes. Because AP-2 is exclusively associated with plasma membrane clathrin coats, our observations imply that a significant population of Lamps traffic via the plasma membrane en route to lysosomes.

scholarly journals Mixed-subunit capsids can be assembled in vitro with coat protein subunits from two cucumoviruses

1995 ◽  
Vol 76 (4) ◽  
pp. 971-973 ◽  
Author(s):  
B. Chen ◽  
J. W. Randles ◽  
R. I. B. Francki
Keyword(s):  
Coat Protein ◽  
Protein Subunits

The coat protein subunits of N4 coliphage

1967 ◽  
Vol 28 (4) ◽  
pp. 611-615 ◽  
Author(s):  
G.C. Schito ◽  
A.M. Molina ◽  
A. Pesce
Keyword(s):  
Coat Protein ◽  
Protein Subunits

scholarly journals The Use of 2-Chloroethanol for Reversible Depolymerisation of the Protein Shell of Bacteriophage fr

1970 ◽  
Vol 25 (7) ◽  
pp. 711-713 ◽  
Author(s):  
D. Schubert ◽  
H. Frank
Keyword(s):  
Acetic Acid ◽  
Ionic Strength ◽  
Organic Solvent ◽  
High Ionic Strength ◽  
Protein Subunits ◽  
Viruslike Particles ◽  
Low Ionic Strength ◽  
Protein Shell

In mixtures of 1 volume of buffer and 2 volumes of 2-chloroethanol, the icosahedral bacteriophage fr is split into RNA and monomeric protein subunits. After removal of the RNA and after replacement of the organic solvent by water, viruslike particles can be obtained by dialysis of the protein against neutral buffers of high ionic strength, whereas multishell particles are formed in buffers of low ionic strength. All results achieved by the use of 2-chloroethanol are very similar to those obtained using acetic acid.

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