Remm M, Remm A, Ustav M
Department of Microbiology and Virology, University of Tartu, and Estonian Biocentre, Tartu 51010, Estonia.
J Virol. 1999 Apr;73(4):3062-70. doi: 10.1128/JVI.73.4.3062-3070.1999.
Papillomaviruses are small double-stranded DNA viruses that replicate episomally in the nuclei of infected cells. The full-length E1 protein of papillomaviruses is required for the replication of viral DNA. The viral mRNA from which the human papillomavirus type 18 E1 protein is expressed is not known. We demonstrate that in eukaryotic cells, the E1 protein is expressed from polycistronic mRNA containing E6, E7, and E1 open reading frames (ORFs). The translation of adjacent E7 and E1 ORFs is not associated; it is performed by separate populations of ribosomes. The translation of the downstream E1 gene is preceded by ribosome scanning. Scanning happens at least at the 5' end of the polycistronic mRNA and also approximately 100 bp in front of the E1 gene. Long areas in middle of the mRNA are bypassed by ribosomes, possibly by ribosomal "shunting." Inactivation of short minicistrons in the upstream area of the E1 gene did not change the expression level of the E1 gene.
乳头瘤病毒是小型双链DNA病毒，在受感染细胞的细胞核中进行游离型复制。乳头瘤病毒的全长E1蛋白是病毒DNA复制所必需的。目前尚不清楚表达人乳头瘤病毒18型E1蛋白的病毒mRNA。我们证明，在真核细胞中，E1蛋白由包含E6、E7和E1开放阅读框（ORF）的多顺反子mRNA表达。相邻的E7和E1 ORF的翻译不相关；它由不同的核糖体群体进行。下游E1基因的翻译之前有核糖体扫描。扫描至少发生在多顺反子mRNA的5'端，也发生在E1基因前方约100 bp处。mRNA中间的长区域可能通过核糖体“跳跃”被核糖体跳过。E1基因上游区域的短微型顺反子失活不会改变E1基因的表达水平。
