Arzt Steffi, Petit Isabelle, Burmeister Wilhelm P, Ruigrok Rob W H, Baudin Florence
European Synchrotron Radiation Facility, BP 220, 38043 cedex 09, Grenoble, France.
Virus Res. 2004 Feb;99(2):115-9. doi: 10.1016/j.virusres.2003.10.010.
The influenza virus M1 (matrix) protein forms the connection between the membrane component of the virus and its replication component eight ribonucleoprotein particles (RNPs). For this activity, M1 self-polymerises in the infected cell in order to pull glycoprotein containing membrane segments together. Later in the process of infection, M1 enters the nucleus and is active in the nuclear export process of newly made RNPs for virus particle assembly. The N-terminal domain (residues 1-164) of M1 carries the nuclear localisation sequence (NLS) motif and is important for membrane binding, self-polymerisation and nuclear export of RNPs. An NLS-mutant M1 has been used in functional studies in order to implicate the positive charges in the NLS in these three activities. In this paper, the crystal structure of the N-terminal domain of this NLS-mutant is determined and is found to be the same as that of the wild-type protein, clearly indicating that it is the absence of the positively charged residues of the NLS that causes the knock-out phenotype rather than a change in the overall structure of the mutant protein.
流感病毒M1（基质）蛋白在病毒的膜成分与其复制成分八个核糖核蛋白颗粒（RNP）之间形成连接。为了实现这一功能，M1在受感染细胞中自我聚合，以便将含有糖蛋白的膜片段聚集在一起。在感染过程的后期，M1进入细胞核，并在新合成的RNP用于病毒颗粒组装的核输出过程中发挥作用。M1的N端结构域（第1至164位氨基酸残基）携带核定位序列（NLS）基序，对RNP的膜结合、自我聚合和核输出很重要。为了研究NLS中的正电荷在这三种活性中的作用，一种NLS突变体M1已被用于功能研究。在本文中，确定了这种NLS突变体N端结构域的晶体结构，发现其与野生型蛋白相同，这清楚地表明，导致敲除表型的原因是NLS中带正电荷残基的缺失，而不是突变蛋白整体结构的改变。
