Download or read book Translation Initiation Factors EIF4B and EIF4H Stimulate the Ribonuclease Activity of the Virion Host Shutoff Protein of Herpes Simplex Virus 1 written by Rosalyn C. Doepker and published by . This book was released on 2004 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advances in Virus Research written by and published by Elsevier. This book was released on 2006-08-03 with total page 421 pages. Available in PDF, EPUB and Kindle. Book excerpt: Published since 1953, Advances in Virus Research covers a diverse range of in-depth reviews providing a valuable overview of the current field of virology. In 2004, the Institute for Scientific Information released figures showing that the series has an Impact Factor of 2.576, with a half-life of 7.1 years, placing it 11th in the highly competitive category of Virology.
Download or read book Index Medicus written by and published by . This book was released on 2004 with total page 1876 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vols. for 1963- include as pt. 2 of the Jan. issue: Medical subject headings.
Download or read book Understanding Viruses written by Teri Shors and published by Jones & Bartlett Publishers. This book was released on 2017 with total page 969 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding Viruses continues to set the standard for the fundamentals of virology. This classic textbook combines molecular, clinical, and historical aspects of human viral diseases in a new stunning interior design featuring high quality art that will engage readers. Preparing students for their careers, the Third Edition greatly expands on molecular virology and virus families. This practical text also includes the latest information on influenza, global epidemiology statistics, and the recent outbreaks of Zika and Ebola viruses to keep students on the forefront of cutting-edge virology information. Numerous case studies and feature boxes illuminate fascinating research and historical cases stimulate student interest, making the best-selling Understanding Viruses the clear choice in virology. Each new print copy includes Navigate 2 Advantage Access that unlocks a comprehensive and interactive eBook, student practice activities and assessments, a full suite of instructor resources (available to adopting instructors with course ID), and learning analytics reporting tools (available to adopting instructors with course ID).
Download or read book The Role of Host Translation Initiation Factors EIF4H and EIF4A and the Exon Junction Complex in the Control of MRNA Turnover and Translation by the Virion Host Shut Off Protein of Herpes Simplex Virus written by Jouliana Sadek and published by . This book was released on 2013 with total page 185 pages. Available in PDF, EPUB and Kindle. Book excerpt: During lytic infections, the HSV Vhs endonuclease (UL41) degrades many viral and cellular mRNAs. This endonuclease activity is dependent upon the ability of Vhs to bind the host translation initiation factors eIF4AI/II and eIF4H. eIF4AI and 4AII are isoforms of an ATP-dependent RNA helicase that unwinds mRNA secondary structure near the 5’ cap to allow the binding and subsequent scanning of the 40S ribosomal subunit. eIF4H binds and stimulates the helicase activity of eIF4AI/II. Si-RNA mediated knockdown of both eIF4AI/AII isoforms significantly impeded Vhs activity. Furthermore, hippuristanol, a selective eIF4AI/II inhibitor, blocked Vhs-mediated mRNA decay both in vitro and in vivo. In addition, we can restore Vhs activity in cells depleted of their endogenous eIF4H protein levels by transfecting an expression vector that encodes wild-type eIF4H but lacks the sequences recognized by the siRNA. We used this assay to screen a library of mutant eIF4H polypeptides for their ability to participate in Vhs cleavage and assayed their ability to bind eIF4A. These experiments revealed that both binding and stimulating eIF4A helicase activity are required for Vhs activity. In addition, we showed that the splicing history of an mRNA can affect its expression levels and its sensitivity to cleavage by Vhs. In uninfected cells, spliced mRNAs bound by the exon junction complex (EJC) are translated more efficiently than unspliced mRNAs containing an identical primary sequence. Whereas most cellular mRNAs are spliced, most viral mRNAs are not except a few immediate-early and late genes. During HSV-1 infections, spliced mRNAs containing a luciferase reporter were much less sensitive to Vhs-mediated degradation and expressed significantly more RLuc protein per molecule of mRNA, than did the unspliced mRNAs. The intron translational stimulatory effect could be replicated by artificially tethering various EJC components to an intronless RLuc reporter. Furthermore, knocking down the expression of endogenous eIF4AIII, an essential component of the EJC, restores Vhs cutting of spliced transcripts to the same level as unspliced mRNAs. The data suggest that the exon junction complex plays an important role in gene expression during HSV infections and can temporarily protect spliced mRNAs from Vhs endonuclease activity.
Download or read book Alpha Herpesviruses written by Rozanne Marie Sandri-Goldin and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Herpes Simplex Virus Virion Host Shutoff Protein is Targeted to MRNA Cleavage Sites Through Interactions with Components of the Host Translational Apparatus written by Lora Ann Shiflett and published by . This book was released on 2010 with total page 185 pages. Available in PDF, EPUB and Kindle. Book excerpt: The virion host shutoff protein (Vhs) is a herpes simplex virus (HSV) protein involved in early shutoff of the host cell. It is a component of the infecting virion, located in the tegument region, that works by rapidly degrading both viral and cellular messenger RNA (mRNA). in vivo and within infected cells, Vhs is selective for degrading messenger RNA opposed to non-messenger RNA. This dissertation sought to examine Vhs cleavage of an mRNA that utilizes the cap-dependent scanning mechanism for translation initiation and to see if cleavage was connected to early events of translation initiation. mRNA encoding HSV-1 thymidine kinase (pBK2) was used for the majority of the experiments, and studies were designed to map the cut sites produced by Vhs in a rabbit reticulocyte lysate (RRL) system. Additional experiments investigated whether Vhs was selective for degrading certain types of mRNAs over others, particularly IRES-containing mRNAs. Studies revealed that Vhs specifically cleaves pBK2 mRNA within the first 300 bases from the 5' cap, and these cut sites are close to and slightly upstream from the first three AUG codons of the sequence. The proximity of the cutting to the AUG codons led to speculations that early events of translation initiation might be involved in Vhs degradation of mRNA. This was found to be true, where data revealed that blocking early stages such as (1) recruitment of translation initiation factors to the 5' cap and/or (2) ATP hydrolysis RNA helicase activity important for unwinding RNA secondary structure and the scanning process hinder Vhs cleavage. However, blocking later stages of translation initiation only had a modest effect on RNase activity. Results also found that a 5' cap analog inhibits Vhs site-specific cleavage of mRNA at regions near the 5' cap. Interestingly, a cap appears to be required for Vhs production of specific cleavage sites within the first 300 bases of the transcript. Work went on to study whether there was a difference between Vhs cleavage of circularized RNA that normally experiences cap-dependent scanning and circularized RNA that initiates translation in a cap-independent manner. Results indicated that Vhs requires a free 5' end for specific cleavage of mRNA that undergoes cap-dependent scanning. However, Vhs does not require a free 5' end to specifically cleave a circular RNA that utilizes cap-independent methods for translation initiation. Mutational work, with pBK2 mutants which contained mutations in or surrounding the AUG codon, further supported a mechanism for Vhs cleavage that involved Vhs association with the scanning complex to reach some of its preferred cut sites. Mutating the first AUG to a non-AUG inhibited Vhs specific cleavage of pBK2 mRNA at a region just upstream from the AUG codon. Additionally, mutating bases surrounding the AUG codon to put it in an optimal context enhanced cleavage at regions near the start codon. Inserting a stable hairpin near the 5' cap to block scanning also reduced Vhs cleavage at prominent sites within the first 300 bases of the transcript. To conclude, this work provides several indications that Vhs associates with components of the translational apparatus to access at least some of its cut sites.
Download or read book Linker Insertion Mutagenesis of the HSV Virion Host Shutoff Protein Mapping Domains Required for Binding Cellular Translation Factors written by Deepali Agarwal and published by . This book was released on 2008 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt: eIF4H shares regions of homology with eukaryotic translation initiation factor eIF4B and the Vhs interaction domain of eIF4H overlaps the homology region. Thus, it was important to determine whether Vhs binding to eIF4H and eIF4B can be separated genetically. This was studied by examining Vhs mutants binding to eIF4B and eIF4H. Several Vhs mutant polypeptides showed differences in binding to eIF4H and eIF4B. One Vhs mutant was identified that lacks in vivo mRNA degradation activity, even though it is an active endonuclease and binds eIF4AII and eIF4B, suggesting binding of eIF4B is not essential for Vhs induced degradation of mRNAs that are translated by cap dependent scanning.
