Rascle J B, Ficheux D, Darlix J L
Unité de Virologie Humaine U412, Ecole Normale Supérieure de Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France.
J Mol Biol. 1998 Jul 10;280(2):215-25. doi: 10.1006/jmbi.1998.1873.
Retroviral nucleocapsid (NC) protein, in addition to its structural roles in the virion core, is involved in the early and late phases of the viral replication cycle. To further characterise the role of NC protein of MoMuLV (NCp10) in the replication of the viral genome, the influence of NCp10 on self-primed versus primer-specific reverse transcription has been analysed in vitro. The results show that NCp10 can enhance the specificity of proviral DNA synthesis by inhibiting self-primed cDNA synthesis while promoting primer-specific DNA synthesis within active NCp10-RNA nucleoprotein complexes. Retroviruses are known to show a high degree of variability and this prompted us to examine the possible implication of NCp10 in the genetic variability of MoMuLV. The ability of reverse transcriptase (RT) to extend different mutated primers using an RNA or a DNA template has been investigated in the presence or in the absence of NCp10. NCp10 was found to have different effects on RT depending on the nature of the template: an enhancement at the elongation level of mutated primers using RNA as template versus a slight inhibition using DNA as template. These observations suggest that NCp10 could be implicated in the genetic variability of MoMuLV by allowing nucleotide misincorporation principally during minus strand DNA synthesis.
逆转录病毒核衣壳（NC）蛋白，除了在病毒粒子核心中发挥结构作用外，还参与病毒复制周期的早期和晚期阶段。为了进一步阐明莫洛尼鼠白血病病毒（MoMuLV）的NC蛋白（NCp10）在病毒基因组复制中的作用，已在体外分析了NCp10对自引发与引物特异性逆转录的影响。结果表明，NCp10可通过抑制自引发的cDNA合成，同时促进活性NCp10-RNA核蛋白复合物内的引物特异性DNA合成，来增强前病毒DNA合成的特异性。已知逆转录病毒具有高度变异性，这促使我们研究NCp10在MoMuLV遗传变异性中的可能作用。在有或没有NCp10的情况下，研究了逆转录酶（RT）使用RNA或DNA模板延伸不同突变引物的能力。发现NCp10对RT的影响因模板性质而异：以RNA为模板时，在突变引物的延伸水平上增强；以DNA为模板时，则有轻微抑制。这些观察结果表明，NCp10可能主要在负链DNA合成过程中通过允许核苷酸错掺入而参与MoMuLV的遗传变异性。
