MUTATIONAL ANALYSIS OF THE CONSERVED MOTIFS OF INFLUENZA-A VIRUS POLYMERASE BASIC-PROTEIN 1
MUTATIONAL ANALYSIS OF THE CONSERVED MOTIFS OF INFLUENZA-A VIRUS POLYMERASE BASIC-PROTEIN 1
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DOI：
10.1128/jvi.68.3.1819-1826.1994
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发表时间：
1994-03-01
影响因子：
5.4
通讯作者：
NAYAK, DP
中科院分区：
文献类型：
--
作者：
BISWAS, SK;NAYAK, DP
流感病毒聚合酶复合体是由聚合酶碱性蛋白1（PB 1）、聚合酶碱性蛋白2（PB 2）和聚合酶酸性蛋白（PA）组成的异源三聚体。其中，只有参与RNA链延伸的PB 1具有在所有病毒RNA依赖性RNA或RNA依赖性DNA聚合酶中发现的四个保守基序（基序I、II、III和IV）和四个不变氨基酸（每个基序中一个）。我们已经修改了Huang等人（T. J. Huang，P. Palese，and M. Krystal，J. 64：5669-5673，1990）以重建潜水中的功能性聚合酶活性。使用该测定，我们已经检查了PB 1的这些基序中的每一个在聚合酶活性中的要求。我们发现，这些不变的氨基酸中的每一个都是PB 1活性的关键，并且这些残基中的任何一个的突变都会使蛋白质失去功能。我们还发现，在基序III，其中包含的SSDD序列，流感病毒RNA聚合酶的签名序列，SDD基本上是不变的，不能容纳在其他RNA病毒聚合酶中发现的序列。然而，SDD侧翼序列的保守变化可以部分耐受。这些结果提供了实验证据，表明流感病毒PB 1具有与其他RNA病毒相似的聚合酶模块，并且流感病毒PB 1的核心SDD序列代表负链非节段RNA病毒中的GDN、正链RNA病毒和双链RNA病毒中的GDD或逆转录病毒中的MDD的序列变体。
Influenza virus polymerase complex is a heterotrimer consisting of polymerase basic protein 1 (PB1), polymerase basic protein 2 (PB2), and polymerase acidic protein (PA). Of these, only PB1, which has been implicated in RNA chain elongation, possesses the four conserved motifs (motifs I, II, III, and IV) and the four invariant amino acids (one in each motif) found among all viral RNA-dependent RNA or RNA-dependent DNA polymerases. We have modified an assay system developed by Huang et al. (T.-J. Huang, P. Palese, and M. Krystal, J. Virol. 64:5669-5673, 1990) to reconstitute the functional polymerase activity in dive. Using this assay, we have examined the requirement of each of these motifs of PB1 in polymerase activity. We find that each of these invariant amino acids is critical for PB1 activity and that mutation in any one of these residues renders the protein nonfunctional. We also find that in motif III, which contains the SSDD sequence, the signature sequence of influenza virus RNA polymerase, SDD is essentially invariant and cannot accommodate sequences found in other RNA viral polymerases. However, conserved changes in the flanking sequences of SDD can be partially tolerated. These results provide the experimental evidence that influenza virus PB1 possesses a similar polymerase module as has been proposed for other RNA viruses and that the core SDD sequence of influenza virus PB1 represents a sequence variant of the GDN in negative-stranded nonsegmented RNA viruses, GDD in positive-stranded RNA virus and double-stranded RNA viruses, or MDD in retroviruses.