Organization of dsDNA in icosahedral virus capsids

Author(s):  
Frank P. Booy ◽  
Benes L. Trus ◽  
William W. Newcomb ◽  
Jay C. Brown ◽  
Philip Serwer ◽  
...  

Condensation/decondensation reactions which effect the packaging of viral genomes into their capsids and their subsequent release constitute one of the basic phenomena which structural biology seeks to explain. The appropriate nucleic acid molecule(s) must be selected; then packaged at a high density to allow efficient utilization of the available space; the mutual electrostatic repulsion of DNA strands must somehow be overcome; and the arrangement of the DNA must allow for its ready release upon initiation of infection. Cryo-electron microscopy has emerged as an incisive tool for visualizing the internal organization of packaged DNA inside viral capsids. We illustrate its effectiveness with observations relating to bacteriophages T4, T7, and herpes simplex virus, type 1 (HSV-1).

1995 ◽  
Vol 76 (6) ◽  
pp. 1417-1431 ◽  
Author(s):  
D. R. S. Jamieson ◽  
L. H. Robinson ◽  
J. I. Daksis ◽  
M. J. Nicholl ◽  
C. M. Preston

2007 ◽  
Vol 81 (20) ◽  
pp. 10991-11004 ◽  
Author(s):  
Roger D. Everett ◽  
Jill Murray ◽  
Anne Orr ◽  
Chris M. Preston

ABSTRACT Herpes simplex virus type 1 (HSV-1) genomes become associated with structures related to cellular nuclear substructures known as ND10 or promyelocytic leukemia nuclear bodies during the early stages of lytic infection. This paper describes the relationship between HSV-1 genomes and ND10 in human fibroblasts that maintain the viral genomes in a quiescent state. We report that quiescent HSV-1 genomes detected by fluorescence in situ hybridization (FISH) are associated with enlarged ND10-like structures, frequently such that the FISH-defined viral foci are apparently enveloped within a sphere of PML and other ND10 proteins. The number of FISH viral foci in each quiescently infected cell is concordant with the input multiplicity of infection, with each structure containing no more than a small number of viral genomes. A proportion of the enlarged ND10-like foci in quiescently infected cells contain accumulations of the heterochromatin protein HP1 but not other common markers of heterochromatin such as histone H3 di- or trimethylated on lysine residue 9. Many of the virally induced enlarged ND10-like structures also contain concentrations of conjugated ubiquitin. Quiescent infections can be established in cells that are highly depleted for PML. However, during the initial stages of establishment of a quiescent infection in such cells, other ND10 proteins (Sp100, hDaxx, and ATRX) are recruited into virally induced foci that are likely to be associated with HSV-1 genomes. These observations illustrate that the intimate connections between HSV-1 genomes and ND10 that occur during lytic infection also extend to quiescent infections.


2009 ◽  
Vol 83 (10) ◽  
pp. 4963-4977 ◽  
Author(s):  
Roger D. Everett ◽  
Marie-Laure Parsy ◽  
Anne Orr

ABSTRACT Herpes simplex virus type 1 (HSV-1) immediate-early regulatory protein ICP0 is important for stimulating the initiation of the lytic cycle and efficient reactivation of latent or quiescent infection. Extensive investigation has suggested several potential functions for ICP0, including interference in the interferon response, disruption of functions connected with PML nuclear bodies (ND10), and inhibition of cellular histone deacetylase (HDAC) activity through an interaction with the HDAC-1 binding partner CoREST. Analysis of the significance of these potential functions and whether they are direct or indirect effects of ICP0 is complicated because HSV-1 mutants expressing mutant forms of ICP0 infect cells with widely differing efficiencies. On the other hand, transfection approaches for ICP0 expression do not allow studies of whole cell populations because of their limited efficiency. To overcome these problems, we have established a cell line in which ICP0 expression can be induced at levels pertaining during the early stages of HSV-1 infection in virtually all cells in the culture. Such cells enable 100% complementation of ICP0-null mutant HSV-1. Using cells expressing the wild type and a variety of mutant forms of ICP0, we have used this system to analyze the role of defined domains of the protein in stimulating lytic infection and derepression from quiescence. Activity in these core functions correlated well the ability of ICP0 to disrupt ND10 and inhibit the recruitment of ND10 proteins to sites closely associated with viral genomes at the onset of infection, whereas the CoREST binding region was neither sufficient nor necessary for ICP0 function in lytic and reactivating infections.


2002 ◽  
Vol 83 (12) ◽  
pp. 2943-2950 ◽  
Author(s):  
Ying-Hsiu Su ◽  
Michael J. Moxley ◽  
Alan K. Ng ◽  
Judy Lin ◽  
Robert Jordan ◽  
...  

Herpes simplex virus type 1 (HSV-1) DNA has been shown to exist as a linear, double-stranded molecule in the virion and as a non-linear (endless), episomal, nucleosomal form in latently infected trigeminal ganglia. The kinetics of the formation and appearance of endless viral genomes and the stability of linear genomes in neuronal cells are not well understood. Nerve growth factor (NGF)-differentiated PC12 cells can sustain long-term, quiescent infections with HSV-1. In this report, the structure and stability of HSV-1 viral DNA in NGF-differentiated PC12 cells was studied as a function of time following infection using both wild-type and replication-defective virus. Unexpectedly, unencapsidated linear genomes were stable in the nucleus of NGF-differentiated PC12 cells for up to 2–3 weeks following infection, beyond the period at which there is no detectable viral gene expression. However, following infection with wild-type HSV, the majority of quiescent viral genomes were in an endless form after 3–4 weeks. These data suggest that the stability and fate of HSV-1 DNA in non-mitotic neuronal-like cells is different from that in productively infected cells and thus there is a significant cellular role in this process. The relevance to the virus life-cycle in neurones in vivo is discussed.


2005 ◽  
Vol 79 (8) ◽  
pp. 5078-5089 ◽  
Author(s):  
Roger D. Everett ◽  
Jill Murray

ABSTRACT Infections with DNA viruses commonly result in the association of viral genomes and replication compartments with cellular nuclear substructures known as promyelocytic leukemia protein (PML) nuclear bodies or ND10. While there is evidence that viral genomes can associate with preexisting ND10, we demonstrate in this study by live-cell microscopy that structures resembling ND10 form de novo and in association with viral genome complexes during the initial stages of herpes simplex virus type 1 (HSV-1) infection. Consistent with previous studies, we found that the major ND10 proteins PML, Sp100, and hDaxx are exchanged very rapidly between ND10 foci and the surrounding nucleoplasm in live cells. The dynamic nature of the individual protein molecule components of ND10 provides a mechanism by which ND10 proteins can be recruited to novel sites during virus infection. These observations explain why the genomes and replication compartments of DNA viruses that replicate in the cell nucleus are so commonly found in association with ND10. These findings are discussed with reference to the nature, location, and potential number of HSV-1 prereplication compartments and to the dynamic aspects of HSV-1 genomes and viral products during the early stages of lytic infection.


2003 ◽  
Vol 77 (6) ◽  
pp. 3680-3689 ◽  
Author(s):  
Roger D. Everett ◽  
George Sourvinos ◽  
Anne Orr

ABSTRACT At the early stages of herpes simplex virus type 1 (HSV-1) infection, parental viral genomes have a tendency to become juxtaposed to cellular nuclear structures known as PML (promyelocytic leukemia) nuclear bodies or ND10, while the immediate-early (IE) protein ICP0 precisely colocalizes with these structures. Previous indirect-immunofluorescence studies observed that the HSV-1 transcriptional regulator ICP4 has a mainly diffuse nuclear distribution early in infection and is later recruited into viral replication compartments. We have constructed HSV-1 variants expressing ICP4 and ICP0 linked to ECFP and EYFP, respectively, both singly and in combination. Coupled with an efficient method of expressing autofluorescent PML in ND10, we have studied the dynamics of ICP0, ICP4, and ND10 in live, infected cells. The greater sensitivity and lower background signals in live cells revealed that early in infection, ICP4 forms discrete foci, some of which are juxtaposed to ND10, while ICP0 was found to colocalize precisely with PML. As expected from these results, using a double-labeled virus, we observed that foci of ICP0 and ICP4 were also juxtaposed but not colocalized early in infection. Some of the ICP4 foci must have contained parental viral genomes, because they developed into replication compartments. We propose that a proportion of the ND10-associated ICP4 foci represent ICP4 molecules being recruited onto parental viral genomes, a process likely to be a critical step early in lytic infection. These results may be analogous to the localization of IE1 and IE2 during human cytomegalovirus infection, suggesting a principle common to the alpha- and betaherpesviruses.


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