Amino acid substitutions in the effector domain of the gamma(1)34.5 protein of herpes simplex virus 1 have differential effects on viral response to interferon-alpha.
The gamma(1)34.5 protein of herpes simplex virus 1 (HSV-1) is a virus-encoded protein phosphatase 1 (PP1) regulatory protein that contributes to viral resistance to interferon. It functions to block the shutoff of protein synthesis mediated by the double-stranded RNA-dependent protein kinase. This requires the carboxyl terminus of the gamma(1)34.5 protein to recruit PP1, forming a high-molecular-weight complex that dephosphorylates the alpha subunit of translation initiation factor eIF-2 (eIF-2alpha). In the present study, we introduced a series of point mutations into a region in the effector domain of the gamma(1)34.5 protein, which is adjacent to the PP1-binding domain. Analysis of these mutants in virus-infected cells shows that Ser209Ala, Ser209Asp, Ser218Ala, or Trp219Tyr substitution does not affect viral response to interferon-alpha. In contrast, Arg215Leu or Ser218Asp substitution rendered the virus hypersensitive to interferon-alpha, which correlates with the inability of these gamma(1)34.5 mutants to mediate dephosphorylation of eIF-2alpha. However, Arg215Leu or Ser218Asp substitution does not disrupt the formation of a high-molecular-weight complex required for eIF-2alpha dephosphorylation or binding of the gamma(1)34.5 protein to PP1. These results suggest that concerted action of the PP1-binding domain and the effector domain of the gamma(1)34.5 protein is required to confer HSV-1 interferon resistance.
Cerveny
Melissa
M
Department of Microbiology and Immunology, College of Medicine, The University of Illinois at Chicago, 60612, USA.
Hessefort
Suzanne
S
Yang
Kui
K
Cheng
Guofeng
G
Gross
Martin
M
He
Bin
B
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology*; D002460:Cell Line; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism; D018259:Herpesvirus 1, Human / Q000187:drug effects*; D006801:Humans; D016898:Interferon-alpha / Q000494:pharmacology*; D008969:Molecular Sequence Data; D010749:Phosphoprotein Phosphatases / Q000502:physiology; D054645:Protein Phosphatase 1; D013329:Structure-Activity Relationship; D014764:Viral Proteins / Q000737:chemistry* / Q000502:physiology
D000998:Antiviral Agents; D015852:Eukaryotic Initiation Factor-2; D016898:Interferon-alpha; D014764:Viral Proteins; C066469:gamma 34.5 protein, Human herpesvirus 1; C019363:eIF-2 phosphatase; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1