- 作者: Yung-Nien Chang; Kuan-Teh Jeang; Tom Lietman; Gary S. Hayward
- 作者服務機構: The Molecular Virology Laboratories, Department of Pharmacology and; Molecular Sciences, Johns Hopkins School; of Medicine, Baltimore, Md., USA
- 中文摘要: --
- 英文摘要: Total immediate-early (IE) RNA synthesized after infection with African green monkey cytomegalovirus (SCMV) in the presence of cycloheximide con- tained a major 2.3-kb mRNA species that acted as template for in vitro synthe- sis of a single 94-kD nuclear protein. The same IE RNA hybridized predomi- nantly to a 1.8-kb subregion of the 220-kb genome which mapped 1.5 kb to the left of the in vitro transcription start site and TATATAA motif previously associated with the powerful MIE (IE94) enhancer region. However, DNA sequence and S1-mapping analysis of a 5-kb region downstream from the pro- moter revealed the existence of a far upstream noncoding first exon and four additional spliced exons capable of encoding two alternative protein products with shared N-terminal domains. This region is similar in structure to that of the MIE gene complex of human cytomegalovirus (HCMV), including being highly CpG suppressed. Exons 2, 3, and 4 encode an acidic protein equivalent to the 68-kD IE1 protein (UL123) of HCMV and exons 2, 3, and 5 encode a protein equivalent to the 80-kD IE2 (UL122) DNA-binding protein of HCMV. Transcripts from across the IE2 region were detected within the cycloheximide RNA, but they were present at 10- to 20-fold lower abundance than IE1 transcripts. The proposed 547-codon IE1 (IE94) acidic phosphopro- tein of SCMV displays minimal residual homology with the IE1 protein of HCMV, but both associate with metaphase chromosomes and have large C- terminal glutamic-acid-rich domains. In contrast, the proposed 583-codon IE2 protein of SCMV displays extensive amino acid similarity to the HCMV IE2 transcriptional regulatory protein especially within C-terminal domains that are known to play a major role in promoter targeting for both transactivation and negative autoregulation functions.
- 中文關鍵字: --
- 英文關鍵字: Nuclear regulatory proteins; Bicistronic genes; Homologous protein domains