Gros C, Wengler G
Institut für Virologie, Justus-Liebig-Universität Giessen, Germany.
Virology. 1996 Mar 1;217(1):367-72. doi: 10.1006/viro.1996.0125.
The replicative proteins of Rubella virus are generated from a polyprotein that is translated from the 5'-terminal segment of the viral genome. The determination of the genome sequence and the description of amino acid sequence motifs which are proposed to be characteristic for helicase proteins have indicated that the polyprotein region located between amino acid residues 1300 and 1600 represents the Rubella virus helicase. We have expressed a segment comprising the sequences between the amino acid residues A (1225) and R (1664) as part of a glutathione S-transferase fusion protein in Escherichia coli. We show that this protein contains a nucleoside triphosphatase activity which hydrolyses all eight ribonucleoside- and deoxyribonucleoside triphosphates. The activity of the protein, determined by ATP hydrolysis, was influenced by the presence of single-stranded RNA; it was stimulated about 1.7 fold in the presence of poly(U), poly(C), or poly(dT) and inhibited to half its activity in the presence of poly(G). These functions represent characteristic helicase partial functions and provide experimental support for the predicted localization of the helicase in the nonstructural polyprotein.
风疹病毒的复制蛋白由一种多聚蛋白产生，该多聚蛋白从病毒基因组的5'末端片段翻译而来。病毒基因组序列的确定以及对被认为是解旋酶蛋白特征的氨基酸序列基序的描述表明，位于氨基酸残基1300和1600之间的多聚蛋白区域代表风疹病毒解旋酶。我们在大肠杆菌中表达了一段包含氨基酸残基A（1225）和R（1664）之间序列的片段，作为谷胱甘肽S-转移酶融合蛋白的一部分。我们发现该蛋白具有核苷三磷酸酶活性，可水解所有八种核糖核苷三磷酸和脱氧核糖核苷三磷酸。通过ATP水解测定的该蛋白活性受单链RNA的存在影响；在聚（U）、聚（C）或聚（dT）存在下，其活性被刺激约1.7倍，而在聚（G）存在下，其活性被抑制至一半。这些功能代表了解旋酶的特征性部分功能，并为预测的解旋酶在非结构多聚蛋白中的定位提供了实验支持。
