Replication and Recombination of Herpes Simplex Virus DNA
ABSTRACT Replication of herpes simplex virus takes place in the cell nucleus and is carried out by a replisome composed of six viral proteins: the UL30-UL42 DNA polymerase, the UL5-UL8-UL52 helicase-primase, and the UL29 single-stranded DNA-binding protein ICP8. The replisome is loaded on origins of replication by the UL9 initiator origin-binding protein. Virus replication is intimately coupled to recombination and repair, often performed by cellular proteins. Here, we review new significant developments: the three-dimensional structures for the DNA polymerase, the polymerase accessory factor, and the single-stranded DNA-binding protein; the reconstitution of a functional replisome in vitro; the elucidation of the mechanism for activation of origins of DNA replication; the identification of cellular proteins actively involved in or responding to viral DNA replication; and the elucidation of requirements for formation of replication foci in the nucleus and effects on protein localization.
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- "ICP8 also binds to RNA albeit with reduced affinity compared to its ssDNA binding activity . Functionally, ICP8 performs a critical role at the viral DNA replication fork by maintaining ssDNA regions and by interacting with various other replisome components via specific protein–protein interactions [reviewed in     ]. In addition, ICP8 has been demonstrated to function as a recombinase, capable of promoting strand annealing and strand invasion as well as mediating strand exchange reactions in conjunction with the HSV-1 helicase-primase or UL12 nuclease    . "
ABSTRACT: We have adapted the thermal shift assay to measure the ligand binding properties of the herpes simplex virus-I single-strand DNA binding protein, ICP8. By measuring SYPRO Orange fluorescence in microtiter plates using a fluorescence-enabled thermal cycler, we have quantified the effects of oligonucleotide ligands on the melting temperature of ICP8. We found that single-stranded oligomers raise the melting temperature of ICP8 in a length- and concentration-dependent manner, ranging from I C for (dT)(5) to a maximum of 9 C with oligomers >= 10 nucleotides, with an apparent K-d of <1 mu M for (dT)(20). Specifically, the results indicate that ICP8 is capable of interacting with oligomers as short as 5 nucleotides. Moreover, the observed increases in melting temperature of up to 9 degrees C, indicates that single-strand DNA binding significantly stabilizes the structure of ICP8. This assay may be applied to investigate the ligand binding proteins of other single-strand DNA binding proteins and used as a high-throughput screen to identify compounds with therapeutic potential that inhibit single-strand DNA binding. As proof of concept, the single-strand DNA binding agent ciprofloxacin reduces the ligand induced stabilization of the melting temperature of ICP8 in a dose-dependent manner.Biochemical and Biophysical Research Communications 11/2014; 454(4). DOI:10.1016/j.bbrc.2014.10.145 · 2.28 Impact Factor
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- "Following nuclear entry, the linear genome circularizes before the advent of viral protein production (Garber et al., 1993; Strang & Stow, 2005). During lytic infection, early genome replication is achieved by a theta replication mechanism initiated at three redundant origins of replication (two copies of oriS and one copy of oriL) but rolling circle replication later predominates, forming ‘endless’ DNA lacking termini (reviewed by Boehmer & Nimonkar, 2003; Muylaert et al., 2011). This concatemeric DNA is later cleaved to monomeric units during packaging into newly formed capsids. "
ABSTRACT: Herpes simplex virus type 1 is a neurotropic herpesvirus that establishes latency within sensory neurones. Following primary infection, the virus replicates productively within mucosal epithelial cells and enters sensory neurones via nerve termini. The virus is then transported to neuronal cell bodies where latency can be established. Periodically, the virus can reactivate to resume its normal lytic cycle gene expression programme and result in the generation of new virus progeny that are transported axonally back to the periphery. The ability to establish lifelong latency within the host and to periodically reactivate to facilitate dissemination is central to the survival strategy of this virus. Although incompletely understood, this review will focus on the mechanisms involved in the regulation of latency that centre on the functions of the virus-encoded latency-associated transcripts (LATs), epigenetic regulation of the latent virus genome and the molecular events that precipitate reactivation. This review considers current knowledge and hypotheses relating to the mechanisms involved in the establishment, maintenance and reactivation herpes simplex virus latency.FEMS microbiology reviews 12/2011; 36(3):684-705. DOI:10.1111/j.1574-6976.2011.00320.x · 13.81 Impact Factor
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ABSTRACT: Baculoviruses were first identified as insect-specific pathogens, and it was this specificity that lead to their use as safe, target specific biological pesticides. For the past 30 years, AcMNPV has served as the subject of intense basic molecular research into the baculovirus infectious cycle including the interaction of the virus with a continuous insect cell line derived from Spodoptera frugiperda. The studies on baculoviruese have led to an in-depth understanding of the physical organization of the viral genomes including many complete genomic sequences, the time course of gene expression, and the application of this basic research to the use of baculoviruses not only as insecticides, but also as a universal eukaryotic protein expression system, and a potential vector in gene therapy. A great deal has also been discovered about the viral genes required for the replication of the baculovirus genome, while much remains to be learned about the mechanism of viral DNA replication. This report outlines the current knowledge of the factors involved in baculovirus DNA replication, using data on AcMNPV as a model for most members of the Baculoviridae.Virologica Sinica 08/2009; 24(4):243-267. DOI:10.1007/s12250-009-3047-y