Hutchinson K L, Herman R C, Hunt D M
Department of Microbiology and Immunology, University of South Carolina School of Medicine, Columbia 29208.
Virology. 1992 Jul;189(1):67-78. doi: 10.1016/0042-6822(92)90682-f.
Electron microscopy suggested that the mRNA produced in vitro by tsG16(I), a temperature-sensitive mutant of vesicular stomatitis virus, contained an increased proportion of polycistronic mRNAs. Using hybrid selection, we found that the poly(A)+ mRNA synthesized in vitro by tsG16(I) contained approximately two to three times more polycistronic mRNA than did poly(A)+ mRNA synthesized in vitro by the parental wild-type (wt) virus. The increase in polycistronic mRNA occurred at all intergenic junctions examined. In vitro, tsG16(I) has an increased polyadenylation phenotype and a temperature-sensitive transcriptase activity that appear to be due to different mutations. Partial revertants of tsG16(I), which have lost the aberrant polyadenylation phenotype but retain the in vitro thermosensitive transcriptase, produced wt amounts of polycistronic mRNA. This suggested that the increased production of polycistronic mRNA by tsG16(I) may be associated with the increased polyadenylation phenotype of this mutant. These data further support the hypothesis that an increase in size of poly(A) tracts is associated with increased production of polycistronic mRNA.
电子显微镜检查表明，水疱性口炎病毒的温度敏感突变体tsG16(I)在体外产生的mRNA中，多顺反子mRNA的比例增加。通过杂交筛选，我们发现tsG16(I)在体外合成的聚腺苷酸加尾（poly(A)+）mRNA所含的多顺反子mRNA比亲本野生型（wt）病毒在体外合成的poly(A)+ mRNA多大约两到三倍。在所检测的所有基因间连接处，多顺反子mRNA均有增加。在体外，tsG16(I)具有增加的聚腺苷酸化表型和温度敏感的转录酶活性，这似乎是由不同的突变引起的。tsG16(I)的部分回复突变体失去了异常的聚腺苷酸化表型，但保留了体外热敏转录酶，其产生的多顺反子mRNA量与野生型相当。这表明tsG16(I)多顺反子mRNA产量的增加可能与其增加的聚腺苷酸化表型有关。这些数据进一步支持了这样的假说，即聚(A)尾长度的增加与多顺反子mRNA产量的增加相关。
