Sun Jianhe, Cai Ying, Moll Wulf-Dieter, Guo Peixuan
Department of Pathobiology, Purdue Cancer Center and Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA.
Nucleic Acids Res. 2006;34(19):5482-90. doi: 10.1093/nar/gkl701. Epub 2006 Oct 4.
Bacteriophage phi29 utilizes a motor to translocate genomic DNA into a preformed procapsid. The motor contains six pRNAs, an enzyme and one 12-subunit connector with a central channel for DNA transportation. A 20-residue peptide containing a His-tag was fused to the N-terminus of the connector protein gp10. This fusion neither interfered with procapsid assembly nor affected the morphology of the prolate-shaped procapsid. However, the pRNA binding and virion assembly activity were greatly reduced. Such decreased functions can be switched back on by the removal of the tag via protease cleavage, supporting the previous finding that the N-terminus of gp10 is essential for the pRNA binding. The DNA-packaging efficiency with dimeric pRNA was more seriously affected by the extension than with monomeric pRNA. It is speculated that the fusion of the tag generated physical hindrance to pRNA binding, with greater influence for the dimers than the monomers due to their size. These results reveal a potential to turn off and turn on the motor by attaching or removing, respectively, a component to outer part of the motor, and offers an approach for the inhibition of viral replication by using a drug or a small peptide targeted to motor components.
噬菌体phi29利用一种马达将基因组DNA转运到预先形成的原衣壳中。该马达包含六个pRNA、一种酶和一个带有用于DNA运输的中央通道的12亚基连接器。一个含有His标签的20个残基的肽与连接器蛋白gp10的N端融合。这种融合既不干扰原衣壳组装，也不影响长形原衣壳的形态。然而，pRNA结合和病毒体组装活性大大降低。通过蛋白酶切割去除标签可以恢复这种降低的功能，这支持了之前的发现，即gp10的N端对pRNA结合至关重要。与单体pRNA相比，二聚体pRNA的DNA包装效率受该延伸的影响更严重。据推测，标签的融合对pRNA结合产生了物理阻碍，由于二聚体的大小，其对二聚体的影响比对单体的影响更大。这些结果揭示了通过分别在马达外部附着或去除一个组件来关闭和开启马达的可能性，并提供了一种通过使用靶向马达组件的药物或小肽来抑制病毒复制的方法。
