Two proline residues are essential in the calcium-binding activity of rotavirus VP7 outer capsid protein
Two proline residues are essential in the calcium-binding activity of rotavirus VP7 outer capsid protein
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DOI：
10.1128/jvi.71.3.2211-2216.1997
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发表时间：
1997-03-01
影响因子：
5.4
通讯作者：
Cohen, J
中科院分区：
文献类型：
--
作者：
Gajardo, R;Vende, P;Cohen, J
轮状病毒外壳的成熟和稳定性是钙依赖的过程。先前已经表明，来自轮状病毒颗粒的Ca 2+增溶外衣壳蛋白的浓度取决于病毒株。病毒颗粒的这种特性与编码VP 7的基因（基因9）有关。本研究通过分析在低[Ca ~（2+）]选择压力下制备的抗性病毒的基因9的来源，证实了VP 7与低[Ca ~（2+）]抗性的相关性。化学诱变后，我们选择了对低[Ca 2 +]更具抗性的牛RF株突变病毒。编码这些独立突变体的VP 7蛋白的基因已被测序。序列分析证实，这些突变体是独立的，并揭示了突变体VP 7蛋白具有脯氨酸75改变为亮氨酸，并具有在低[Ca 2 +]下溶解的外部衣壳。除了两个突变体之外，在所有突变体中均发现脯氨酸279突变为丝氨酸。具有单个脯氨酸变化的突变体的表型可以与具有两个脯氨酸变化的突变体的表型区分开。序列分析表明，75位氨基酸位于变异较大的区域（氨基酸65 - 78），75位脯氨酸在大多数牛品系中存在，而279位脯氨酸位于保守区域，在数据库中所有的VP 7序列中都是保守的。该区域富含正确分配在Ca 2+结合EF-手结构模式的金属配位位置的含氧残基，表明该区域在VP 7的Ca 2+结合中是重要的。
Rotavirus maturation and stability of the outer capsid are calcium-dependent processes. It has been shown previously that the concentration of Ca2+-solubilizing outer capsid proteins from rotavirus particles is dependent on the virus strain. This property of viral particles has been associated with the gene coding for VP7 (gene 9), In this study the correlation between VP7 and resistance to low [Ca2+] was confirmed by analyzing the origin of gene 9 from reassortant viruses prepared under the selective pressure of low [Ca2+]. After chemical mutagenesis, we selected mutant viruses of the bovine strain RF that are more resistant to low [Ca2+]. The genes coding for the VP7 proteins of these independent mutants have been sequenced. Sequence analysis confirmed that these mutants are independent and revealed that an mutant VP7 proteins have proline 75 changed to leucine and have an outer capsid that solubilized at low [Ca2+]. The mutation of proline 279 to serine is found in all but two mutants, The phenotype of mutants having a single proline change can be distinguished from the phenotype of mutants having two proline changes. Sequence analysis showed that position 75 is in a region (amino acids 65 to 78) of great variability and that proline 75 is present in most of the bovine strains, In contrast proline 279 is in a conserved region and is conserved in all the VP7 sequences in data banks. This region is rich in oxygenated residues that are correctly allocated in the metal-coordinating positions of the Ca2+-binding EF-hand structure pattern, suggesting that this region is important in the Ca2+ binding of VP7.