scholarly journals Mapping the minimal regions within the ORF73 protein required for herpesvirus saimiri episomal persistence

2008 ◽  
Vol 89 (11) ◽  
pp. 2843-2850 ◽  
Author(s):  
Rhoswyn Griffiths ◽  
Sally M. Harrison ◽  
Stuart Macnab ◽  
Adrian Whitehouse
Keyword(s):  
Viral Genome ◽  
Recombinant Virus ◽  
Herpesvirus Saimiri ◽  
Repeat Region ◽  
Mitotic Chromosomes ◽  
C Terminus ◽  
Associated Proteins ◽  
Episomal Maintenance ◽  
Protein Mecp2 ◽  
Terminal Repeat Region

Herpesvirus saimiri (HVS) establishes a persistent infection in which the viral genome persists as a circular non-integrated episome. ORF73 tethers HVS episomes to host mitotic chromosomes, allowing episomal persistence via an interaction with the chromosome-associated protein, MeCP2. Here we demonstrate that ORF73 also interacts with the linker histone H1 via its C terminus, suggesting it associates with multiple chromosome-associated proteins. In addition, we show that the C terminus is also required for the ability of ORF73 to bind the terminal repeat region of the HVS genome. These results suggest that the ORF73 C terminus contains all the necessary elements required for HVS episomal persistence. Using a range of ORF73 C terminus deletions to rescue the episomal maintenance properties of a HVSΔ73 recombinant virus, we show that a C terminus region comprising residues 285–407 is sufficient to maintain the HVS episome in a dividing cell population.

scholarly journals Herpesvirus Saimiri Episomal Persistence Is Maintained via Interaction between Open Reading Frame 73 and the Cellular Chromosome-Associated Protein MeCP2

2007 ◽  
Vol 81 (8) ◽  
pp. 4021-4032 ◽  
Author(s):  
Rhoswyn Griffiths ◽  
Adrian Whitehouse
Keyword(s):  
Open Reading Frame ◽  
Saimiri Sciureus ◽  
Herpesvirus Saimiri ◽  
Nuclear Antigen ◽  
Mitotic Chromosomes ◽  
Reading Frame ◽  
Polycistronic Mrna ◽  
C Terminus ◽  
Associated Proteins ◽  
Acid Domain

ABSTRACT Herpesvirus saimiri (HVS) is the prototype gamma-2 herpesvirus, which naturally infects the squirrel monkey Saimiri sciureus, causing an asymptomatic but persistent infection. The latent phase of gamma-2 herpesviruses is characterized by their ability to persist in a dividing cell population while expressing a limited subset of latency-associated genes. In HVS only three genes, open reading frame 71 (ORF71), ORF72, and ORF73, are expressed from a polycistronic mRNA. ORF73 has been shown to be the only gene essential for HVS episomal maintenance and can therefore be functionally compared to the human gammaherpesvirus latency-associated proteins, EBNA-1 and Kaposi's sarcoma-associated herpesvirus (KSHV) latency-associated nuclear antigen (LANA). HVS ORF73 is the positional homologue of KSHV LANA and, although it shares limited sequence homology, has significant structural and functional similarities. Investigation of KSHV LANA has demonstrated that it is able to mediate KSHV episomal persistence by tethering the KSHV episome to host mitotic chromosomes via interactions with cellular chromosome-associated proteins. These include associations with core and linker histones, several bromodomain proteins, and the chromosome-associated proteins methyl CpG binding protein 2 (MeCP2) and DEK. Here we show that HVS ORF73 associates with MeCP2 via a 72-amino-acid domain within the ORF73 C terminus. Furthermore, we have assessed the functional significance of this interaction, using a variety of techniques including small hairpin RNA knockdown, and show that association between ORF73 and MeCP2 is essential for HVS chromosomal attachment and episomal persistence.

scholarly journals Open reading frame 73 is required for herpesvirus saimiri A11-S4 episomal persistence

2005 ◽  
Vol 86 (10) ◽  
pp. 2703-2708 ◽  
Author(s):  
Michael Calderwood ◽  
Robert E. White ◽  
Rhoswyn A. Griffiths ◽  
Adrian Whitehouse
Keyword(s):  
Recombinant Virus ◽  
Latent Infection ◽  
Mutational Analysis ◽  
Open Reading Frames ◽  
Herpesvirus Saimiri ◽  
Mitotic Chromosomes ◽  
Reading Frame ◽  
The Stability ◽  
Episomal Maintenance

Herpesvirus saimiri (HVS) establishes a latent infection in which the viral genome persists as a non-integrated episome. Analysis has shown that only open reading frames (ORFs) 71–73 are transcribed in an in vitro model of HVS latency. ORF73 also colocalizes with HVS genomic DNA on host mitotic chromosomes and maintains the stability of HVS terminal-repeat-containing plasmids. However, it is not known whether ORF73 is the only HVS-encoded protein required for episomal maintenance. In this study, the elements required for episomal maintenance in the context of a full-length HVS genome were examined by mutational analysis. A recombinant virus, HVS-BACΔ71-73, lacking the latency-associated genes was unable to persist in a dividing cell population. However, retrofitting an ORF73 expression cassette into the recombinant virus rescued episomal maintenance. This indicates that ORF73 is the key trans-acting factor for episomal persistence and efficient establishment of a latent infection.

scholarly journals The herpesvirus saimiri ORF73 gene product interacts with host-cell mitotic chromosomes and self-associates via its C terminus

2004 ◽  
Vol 85 (1) ◽  
pp. 147-153 ◽  
Author(s):  
Michael A. Calderwood ◽  
Kersten T. Hall ◽  
David A. Matthews ◽  
Adrian Whitehouse
Keyword(s):  
Host Cell ◽  
Gene Product ◽  
Herpesvirus Saimiri ◽  
Mitotic Chromosomes ◽  
C Terminus

scholarly journals Mutagenesis of the Herpesvirus Saimiri Terminal Repeat Region Reveals Important Elements for Virus Production

2007 ◽  
Vol 81 (12) ◽  
pp. 6765-6770 ◽  
Author(s):  
Robert E. White ◽  
Lindsay Carline ◽  
Martin J. Allday
Keyword(s):  
Infectious Virus ◽  
Virus Production ◽  
Artificial Chromosome ◽  
Plaque Formation ◽  
Lytic Cycle ◽  
Herpesvirus Saimiri ◽  
Repeat Region ◽  
The Right ◽  
Necessary And Sufficient ◽  
Terminal Repeat Region

ABSTRACT Deletion of the terminal repeats (TR) from herpesvirus saimiri (HVS) renders it unable to produce infectious virus or generate plaques. However, a TR-deleted HVS bacterial artificial chromosome can form replication compartments. Complementation of this mutant shows that one copy of the TR, plus the right junction of the genome with the TR, is sufficient for efficient plaque formation and generation of infectious virus. Within the TR unit, the region around the cleavage site of the genome appears both necessary and sufficient for virus production. Analysis of episomes from productive cells indicates a propensity to amplify TR numbers during the lytic cycle.

Copper complex species within a fragment of the N-terminal repeat region in opossum PrP protein

2011 ◽  
Vol 40 (11) ◽  
pp. 2441 ◽  
Author(s):  
Laura I. Vagliasindi ◽  
Giuseppe Arena ◽  
Raffaele P. Bonomo ◽  
Giuseppe Pappalardo ◽  
Giovanni Tabbì
Keyword(s):  
Copper Complex ◽  
Terminal Repeat ◽  
Repeat Region ◽  
Complex Species ◽  
Terminal Repeat Region

scholarly journals Cbx2 stably associates with mitotic chromosomes via a PRC2- or PRC1-independent mechanism and is needed for recruiting PRC1 complex to mitotic chromosomes

2014 ◽  
Vol 25 (23) ◽  
pp. 3726-3739 ◽  
Author(s):  
Chao Yu Zhen ◽  
Huy Nguyen Duc ◽  
Marko Kokotovic ◽  
Christopher J. Phiel ◽  
Xiaojun Ren
Keyword(s):  
Molecular Mechanisms ◽  
Es Cells ◽  
Epigenetic Inheritance ◽  
Polycomb Group ◽  
Mitotic Chromosomes ◽  
Mouse Es Cells ◽  
C Terminus ◽  
Independent Mechanism ◽  
Cellular Identity ◽  
Quantitative Fluorescence

Polycomb group (PcG) proteins are epigenetic transcriptional factors that repress key developmental regulators and maintain cellular identity through mitosis via a poorly understood mechanism. Using quantitative live-cell imaging in mouse ES cells and tumor cells, we demonstrate that, although Polycomb repressive complex (PRC) 1 proteins (Cbx-family proteins, Ring1b, Mel18, and Phc1) exhibit variable capacities of association with mitotic chromosomes, Cbx2 overwhelmingly binds to mitotic chromosomes. The recruitment of Cbx2 to mitotic chromosomes is independent of PRC1 or PRC2, and Cbx2 is needed to recruit PRC1 complex to mitotic chromosomes. Quantitative fluorescence recovery after photobleaching analysis indicates that PRC1 proteins rapidly exchange at interphasic chromatin. On entry into mitosis, Cbx2, Ring1b, Mel18, and Phc1 proteins become immobilized at mitotic chromosomes, whereas other Cbx-family proteins dynamically bind to mitotic chromosomes. Depletion of PRC1 or PRC2 protein has no effect on the immobilization of Cbx2 on mitotic chromosomes. We find that the N-terminus of Cbx2 is needed for its recruitment to mitotic chromosomes, whereas the C-terminus is required for its immobilization. Thus these results provide fundamental insights into the molecular mechanisms of epigenetic inheritance.

scholarly journals Aip3p/Bud6p, a yeast actin-interacting protein that is involved in morphogenesis and the selection of bipolar budding sites.

1997 ◽  
Vol 8 (4) ◽  
pp. 729-753 ◽  
Author(s):  
D C Amberg ◽  
J E Zahner ◽  
J W Mulholland ◽  
J R Pringle ◽  
D Botstein
Keyword(s):  
Coiled Coil ◽  
Interacting Protein ◽  
Cell Cycles ◽  
Division Site ◽  
Bud Emergence ◽  
C Terminus ◽  
Positional Marker ◽  
Associated Proteins ◽  
Sites Of Action ◽  
Mutant Cells

A search for Saccharomyces cerevisiae proteins that interact with actin in the two-hybrid system and a screen for mutants that affect the bipolar budding pattern identified the same gene, AIP3/BUD6. This gene is not essential for mitotic growth but is necessary for normal morphogenesis. MATa/alpha daughter cells lacking Aip3p place their first buds normally at their distal poles but choose random sites for budding in subsequent cell cycles. This suggests that actin and associated proteins are involved in placing the bipolar positional marker at the division site but not at the distal tip of the daughter cell. In addition, although aip3 mutant cells are not obviously defective in the initial polarization of the cytoskeleton at the time of bud emergence, they appear to lose cytoskeletal polarity as the bud enlarges, resulting in the formation of cells that are larger and rounder than normal. aip3 mutant cells also show inefficient nuclear migration and nuclear division, defects in the organization of the secretory system, and abnormal septation, all defects that presumably reflect the involvement of Aip3p in the organization and/or function of the actin cytoskeleton. The sequence of Aip3p is novel but contains a predicted coiled-coil domain near its C terminus that may mediate the observed homo-oligomerization of the protein. Aip3p shows a distinctive localization pattern that correlates well with its likely sites of action: it appears at the presumptive bud site prior to bud emergence, remains near the tips of small bund, and forms a ring (or pair of rings) in the mother-bud neck that is detectable early in the cell cycle but becomes more prominent prior to cytokinesis. Surprisingly, the localization of Aip3p does not appear to require either polarized actin or the septin proteins of the neck filaments.

scholarly journals Hitchhiking of Viral Genomes on Cellular Chromosomes

2019 ◽  
Vol 6 (1) ◽  
pp. 275-296 ◽  
Author(s):  
Tami L. Coursey ◽  
Alison A. McBride
Keyword(s):  
Viral Genome ◽  
Viral Infections ◽  
Genome Replication ◽  
Mitotic Chromosomes ◽  
Dna Viruses ◽  
Viral Genomes ◽  
Barr Virus ◽  
Dividing Cells ◽  
Viral Genome Replication ◽  
Epstein Barr

Persistent viral infections require a host cell reservoir that maintains functional copies of the viral genome. To this end, several DNA viruses maintain their genomes as extrachromosomal DNA minichromosomes in actively dividing cells. These viruses typically encode a viral protein that binds specifically to viral DNA genomes and tethers them to host mitotic chromosomes, thus enabling the viral genomes to hitchhike or piggyback into daughter cells. Viruses that use this tethering mechanism include papillomaviruses and the gammaherpesviruses Epstein-Barr virus and Kaposi's sarcoma-associated herpesvirus. This review describes the advantages and consequences of persistent extrachromosomal viral genome replication.

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