Differential response of human cells to deletions and stop codons in the gamma(1)34.5 gene of herpes simplex virus.

AUTOR(ES)

Chou, J

RESUMO

Earlier studies have shown that herpes simplex virus mutants lacking the gamma(1)34.5 gene are totally avirulent on intracerebral inoculation of the virus into mice and induce premature shutoff of protein synthesis in human neuroblastoma (SK-N-SH) cells but not in Vero cells. We report the following. (i) Whereas deletion mutant R3616, lacking 1,000 bp of the gamma(1)34.5 gene, caused premature shutoff of protein synthesis in both SK-N-SH and human foreskin fibroblasts (HFF), mutants R4009 and R930 (mutant F), carrying stop codons in all six frames, 27 and 210 codons from the initiation codon of the gamma(1)34.5 genes, respectively, induced shutoff of protein synthesis in SK-N-SH cells but not in HFF. The differences in behavior between the R3616 deletion and R4009 stop codon mutants cannot be attributed to differences in the rate of induction of premature shutoff of protein synthesis and the multiplicity of infection. HFF do not produce detectable truncated gamma(1)34.5 protein or truncated mRNA. (ii) Some clonal lines of SK-N-SH cells carrying a gamma(1)34.5 gene driven by a metallothionein promoter express the gamma(1)34.5 gene constitutively and do not require induction by cadmium to complement the gamma(1)34.5- virus. One clonal cell line complements the gamma(1)34.5- virus only after induction by cadmium. These results are consistent with previous conclusions that the phenotype of premature shutoff of protein synthesis is associated with absence of the gamma(1)34.5 protein and indicate that the amounts of gamma(1)34.5 protein necessary to complement the gamma(1)34.5- viruses are small. We conclude that human cells differ in the manner in which they respond to the presence of stop codons. Shutoff of protein synthesis in HFF infected with the stop codon mutants could have been precluded by small amounts of gamma(1)34.5 protein produced by splicing out of an intron containing the stop codon, downstream initiation of translation, or tRNA suppression of the stop codon.

Documentos Relacionados

• Herpes simplex virus 1 gamma(1)34.5 gene function, which blocks the host response to infection, maps in the homologous domain of the genes expressed during growth arrest and DNA damage.
• Transcription of the derepressed open reading frame P of herpes simplex virus 1 precludes the expression of the antisense gamma(1)34.5 gene and may account for the attenuation of the mutant virus.
• Expression of a herpes simplex virus 1 open reading frame antisense to the gamma(1)34.5 gene and transcribed by an RNA 3' coterminal with the unspliced latency-associated transcript.
• The carboxyl terminus of the murine MyD116 gene substitutes for the corresponding domain of the gamma(1)34.5 gene of herpes simplex virus to preclude the premature shutoff of total protein synthesis in infected human cells.
• The range and distribution of murine central nervous system cells infected with the gamma(1)34.5- mutant of herpes simplex virus 1.