Viral Serine/Threonine Protein Kinases

Department of Virology, Parasitology, and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
Journal of Virology (Impact Factor: 4.44). 11/2010; 85(3):1158-73. DOI: 10.1128/JVI.01369-10
Source: PubMed


Phosphorylation represents one the most abundant and important posttranslational modifications of proteins, including viral
proteins. Virus-encoded serine/threonine protein kinases appear to be a feature that is unique to large DNA viruses. Although
the importance of these kinases for virus replication in cell culture is variable, they invariably play important roles in
virus virulence. The current review provides an overview of the different viral serine/threonine protein kinases of several
large DNA viruses and discusses their function, importance, and potential as antiviral drug targets.

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Available from: Thary Jacob
    • "Kinases are involved in phosphorylation reactions, which are amongst the most abundant and important post-translational modifications of proteins, often regulating protein activities. Virus-encoded serine/threonine protein kinases also appear to be important for virulence regulation of viral infections (Jacob et al., 2011). It is challenging to assign functions to the IIV kinases without expressing them individually in cell culture, unravelling their subcellular localization and identifying the proteins that are specifically phosphorylated. "
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    ABSTRACT: Invertebrate iridescent virus 6 (IIV-6) is a nucleocytoplasmic virus with a 212 kb-long linear double-stranded DNA genome that encodes 215 putative open reading frames. The IIV-6 virion proteome consists of at least 54 virally-encoded proteins. One of our previous findings showed that most of these proteins are encoded by genes from the early transcriptional class. This indicates that these structural proteins may not only function in the formation of the virion, but also in the initial stage of viral infection. In the current study, we followed the protein expression profile of IIV-6 over time in Drosophila S2 cells by label-free quantitation using nanoLC-FTMS. A total of 95 viral encoded proteins were detected in infected cells, of which 37 are virion proteins. The expressed IIV-6 virion proteins could be categorized into three main clusters based on their expression profiles. These clusters were: 1) proteins with stably low or 2) exponentially increased expression levels during infection, and 3) proteins that were initially highly abundant, and then showed slightly reduced levels after 48 hours (h) post infection (p.i.). The study supported that temporal expression patterns did not share direct correlation with protein expression classes phenomena, suggesting that both proteomic and transcriptomic approaches will be required to obtain a detailed understanding of the viral expressomics (infectome). Here, we provide novel information on the kinetics of virion and infected cell-specific protein levels that assists in understanding gene regulation in this lesser known DNA virus model.
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    • "Viral serine/threonine kinases appear to be encoded exclusively by large and evolutionarily old DNA viruses, such as herpesviruses, poxviruses, and baculoviruses (Jacob et al., 2011). Previous data indicated that baculoviral pk-1 encoded a serine/threonine protein kinase which was able to phosphorylate histone H1 in rabbit reticulocyte lysates (Kim and Weaver, 1993; McLachlin et al., 1998) and protamine sulphate (Miller et al., 1983). "
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    ABSTRACT: PK-1 (Ac10) is a baculovirus-encoded serine/threonine kinase and its function is unclear. Our results showed that a pk-1 knockout AcMNPV failed to produce infectious progeny, while the pk-1 repair virus could rescue this defect. qPCR analysis demonstrated that pk-1 deletion did not affect viral DNA replication. Analysis of the repaired recombinants with truncated pk-1 mutants demonstrated that the catalytic domain of protein kinases of PK-1 was essential to viral infectivity. Moreover, those PK-1 mutants that could rescue the infectious BV production defect exhibited kinase activity in vitro. Therefore, it is suggested that the kinase activity of PK-1 is essential in regulating viral propagation. Electron microscopy revealed that pk-1 deletion affected the formation of normal nucleocapsids. Masses of electron-lucent tubular structures were present in cell transfected with pk-1 knockout bacmid. Therefore, PK-1 appears to phosphorylate some viral or cellular proteins that are essential for DNA packaging to regulate nucleocapsid assembly.
    Full-text · Article · Jun 2013 · Virology
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    • "Protein kinases are involved in a wide spectrum of cellular processes and are known to be responsible for modulating the activity of up to 30% of all human proteins [1]. Due to the pivotal role of kinases in cellular activity, it is not surprising that many viruses also encode protein kinases that control host cellular pathways, avoid immune surveillance and regulate viral protein activity [2]. The vaccinia virus (VV) gene B1R encodes an essential 34-kDa protein that has been shown to phosphorylate a variety of both cellular and viral proteins including the tumor suppressor p53 [3-6]. "
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    ABSTRACT: To effectively respond to viral infections, mammals rely on the innate and adaptive immune systems. Additionally, host cellular responses, such as apoptosis also play a vital role in the host defense mechanisms. To accomplish a successful replicative strategy in vivo, animal viruses have evolved a variety of molecular mechanisms that interfere with host responses. Poxviruses in particular, represents a prime example of where animal viruses encode a wide variety of proteins necessary for replication and subversion of the host's immune and single cell responses. Several proteins that inhibit host immmunomodulatory cytokines and apoptosis of infected cells have been characterized in vaccinia virus (VV). Here, we describe the identification of a protein encoded by the tanapox virus genome (142R open reading frame) that is orthologous to the B1R protein from VV. We demonstrate that like B1R, TPV142R encodes a serine threonine kinase that can phosphorylate the tumor suppressor p53 and therefore has the potential for inhibiting apoptosis of infected cells.
    Full-text · Article · Jan 2013 · The Open Virology Journal
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