Site-Directed Mutagenesis of Herpes Simplex Virus Type 1 Thymidine Kinase Opposes the Importance of Amino Acid Position 251, 321 and 348 for Selective Recognition of Substrate Analogs

1995 ◽  
Vol 209 (3) ◽  
pp. 966-973 ◽  
Author(s):  
M. Michael ◽  
J. Fetzer ◽  
G. Folkers
Keyword(s):  
Herpes Simplex Virus ◽  
Amino Acid ◽  
Herpes Simplex ◽  
Amino Acid Position ◽  
Site Directed Mutagenesis ◽  
Selective Recognition ◽  
Directed Mutagenesis ◽  
Substrate Analogs ◽  
Simplex Virus

scholarly journals Dephosphorylation of eIF-2α Mediated by the γ134.5 Protein of Herpes Simplex Virus Type 1 Is Required for Viral Response to Interferon but Is Not Sufficient for Efficient Viral Replication

2003 ◽  
Vol 77 (18) ◽  
pp. 10154-10161 ◽  
Author(s):  
Guofeng Cheng ◽  
Kui Yang ◽  
Bin He
Keyword(s):  
Amino Acids ◽  
Herpes Simplex Virus ◽  
Amino Acid ◽  
Herpes Simplex ◽  
Viral Replication ◽  
Virus Type ◽  
Herpes Simplex Virus Type ◽  
Wild Type ◽  
Simplex Virus

ABSTRACT The γ134.5 protein of herpes simplex virus type 1 (HSV-1) functions to block the shutoff of protein synthesis involving double-stranded RNA-dependent protein kinase (PKR). In this process, the γ134.5 protein recruits cellular protein phosphatase 1 (PP1) to form a high-molecular-weight complex that dephosphorylates eIF-2α. Here we show that the γ134.5 protein is capable of mediating eIF-2α dephosphorylation without any other viral proteins. While deletion of amino acids 1 to 52 from the γ134.5 protein has no effect on eIF-2α dephosphorylation, further truncations up to amino acid 146 dramatically reduce the activity of the γ134.5 protein. An additional truncation up to amino acid 188 is deleterious, indicating that the carboxyl-terminal domain alone is not functional. Like wild-type HSV-1, the γ134.5 mutant with a truncation of amino acids 1 to 52 is resistant to interferon, and resistance to interferon is coupled to eIF-2α dephosphorylation. Intriguingly, this mutant exhibits a similar growth defect seen for the γ134.5 null mutant in infected cells. Restoration of the wild-type γ134.5 gene in the recombinant completely reverses the phenotype. These results indicate that eIF-2α dephosphorylation mediated by the γ134.5 protein is required for HSV response to interferon but is not sufficient for viral replication. Additional functions or activities of the γ134.5 protein contribute to efficient viral infection.

scholarly journals Site-Directed Mutagenesis of the Virion Host Shutoff Gene (UL41) of Herpes Simplex Virus (HSV): Analysis of Functional Differences between HSV Type 1 (HSV-1) and HSV-2 Alleles

1999 ◽  
Vol 73 (11) ◽  
pp. 9117-9129 ◽  
Author(s):  
David N. Everly ◽  
G. Sullivan Read
Keyword(s):  
Amino Acids ◽  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Site Directed Mutagenesis ◽  
Viral Mrnas ◽  
Virion Host Shutoff ◽  
Host Shutoff ◽  
Simplex Virus ◽  
Hsv 1

ABSTRACT During lytic herpes simplex virus (HSV) infections, the HSV virion host shutoff protein (UL41) accelerates the turnover of host and viral mRNAs. Although the UL41 polypeptides from HSV type 1 (HSV-1) strain KOS and HSV-2 strain 333 are 87% identical, HSV-2 strains generally shut off the host more rapidly and completely than HSV-1 strains. In a previous study, we identified three regions of the HSV-2 UL41 polypeptide (amino acids 1 to 135, 208 to 243, and 365 to 492) that enhance the activity of KOS when substituted for the corresponding portions of the KOS protein (D. N. Everly, Jr., and G. S. Read, J. Virol. 71:7157–7166, 1997). These results have been extended through the analysis of more than 50 site-directed mutants of UL41 in which selected HSV-2 amino acids were introduced into an HSV-1 background and HSV-1 amino acids were introduced into the HSV-2 allele. The HSV-2 amino acids R22 and E25 were found to contribute dramatically to the greater activity of the HSV-2 allele, as did the HSV-2 amino acids A396 and S423. The substitution of six HSV-2 amino acids between residues 210 and 242 enhanced the HSV-1 activity to a lesser extent. In most cases, individual substitutions or the substitution of combinations of fewer than all six amino acids reduced the UL41 activity to less than that of KOS. The results pinpoint several type-specific amino acids that are largely responsible for the greater activity of the UL41 polypeptide of HSV-2. In addition, several spontaneous mutations that abolish detectable UL41 activity were identified.

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