Malur Achut G, Gupta Neera K, De Bishnu P, Banerjee Amiya K
Department of Virology, Lerner Research Institute, The Cleveland Clinic Foundation, OH 44195, USA.
Gene Expr. 2002;10(3):93-100.
The large protein (L) of the human parainfluenza virus type 3 (HPIV3) is the functional RNA-dependent RNA polymerase, which possesses highly conserved residues QGDNQ located within motif C of domain III comprising the putative polymerase active site. We have characterized the role of the QGDNQ residues as well as the residues flanking this region in the polymerase activity of the L protein by site-directed mutagenesis and examining the polymerase activity of the wild-type and mutant L proteins by an in vivo minigenome replication assay and an in vitro mRNA transcription assay. All mutations in the QGDNQ residues abolished transcription while mutations in the flanking residues gave rise to variable polymerase activities. These observations support the contention that the QGDNQ sequence is absolutely required for the polymerase activity of the HPIV3 RNA-dependent RNA polymerase.
人副流感病毒3型（HPIV3）的大蛋白（L）是功能性的RNA依赖性RNA聚合酶，其在包含假定聚合酶活性位点的结构域III的基序C内具有高度保守的残基QGDNQ。我们通过定点诱变以及通过体内微型基因组复制试验和体外mRNA转录试验检测野生型和突变型L蛋白的聚合酶活性，来表征QGDNQ残基以及该区域侧翼残基在L蛋白聚合酶活性中的作用。QGDNQ残基中的所有突变均消除了转录，而侧翼残基中的突变则产生了可变的聚合酶活性。这些观察结果支持了这样的论点，即QGDNQ序列对于HPIV3 RNA依赖性RNA聚合酶的聚合酶活性是绝对必需的。
