Anderson D J, Lee P, Levine K L, Sang J S, Shah S A, Yang O O, Shank P R, Linial M L
Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98104-2092.
J Virol. 1992 Jan;66(1):204-16. doi: 10.1128/JVI.66.1.204-216.1992.
The nonconditional RNA packaging mutant SE21Q1b contains cis- and trans-acting defects which cause cellular mRNA, rather than viral genomic RNA, to be nonspecifically packaged into SE21Q1b viral particles. Using genomic libraries of the c-SE21Q1b quail cell line, we have been able to construct a molecular clone of the SE21Q1b provirus. Upon transfection into primary quail embryo fibroblasts, the SE21Q1b molecular clone is able to recapitulate the nonspecific RNA packaging phenotype of the c-SE21Q1b cell line. The RNA packaging phenotypes displayed by several SE21Q1b/avian sarcoma-leukemia virus hybrid provirus constructs have further indicated that sequences responsible for the altered RNA packaging phenotype of SE21Q1b are localized in the left third of the SE21Q1b proviral genome. DNA sequence analysis of this region has revealed that the 5' SE21Q1b deletion has removed 179 bp from the SE21Q1b left long terminal repeat and leader regions. Several differences were detected at the carboxyl terminus of the deduced SE21Q1b nucleocapsid protein sequence in comparison with that of Rous sarcoma virus PR-C. Results of site-directed oligonucleotide mutagenesis experiments indicate, however, that the presence of these residues in the nucleocapsid protein alone is not responsible for the decreased RNA packaging specificity of SE21Q1b.
非条件性RNA包装突变体SE21Q1b存在顺式和反式作用缺陷，这些缺陷导致细胞mRNA而非病毒基因组RNA被非特异性地包装到SE21Q1b病毒颗粒中。利用c-SE21Q1b鹌鹑细胞系的基因组文库，我们成功构建了SE21Q1b前病毒的分子克隆。将其转染到原代鹌鹑胚胎成纤维细胞后，SE21Q1b分子克隆能够重现c-SE21Q1b细胞系的非特异性RNA包装表型。几种SE21Q1b/禽肉瘤白血病病毒杂交前病毒构建体所显示的RNA包装表型进一步表明，导致SE21Q1b RNA包装表型改变的序列位于SE21Q1b前病毒基因组的左三分之一区域。对该区域的DNA序列分析表明，5' SE21Q1b缺失从SE21Q1b左长末端重复序列和前导区域中删除了179 bp。与劳斯肉瘤病毒PR-C相比，在推导的SE21Q1b核衣壳蛋白序列的羧基末端检测到了几个差异。然而，定点寡核苷酸诱变实验结果表明，仅核衣壳蛋白中这些残基的存在并不导致SE21Q1b RNA包装特异性降低。
