A Nuclear Export Signal in the Matrix Protein of Influenza A Virus Is Required for Efficient Virus Replication
A Nuclear Export Signal in the Matrix Protein of Influenza A Virus Is Required for Efficient Virus Replication
复制标题
甲型流感病毒基质蛋白中的核输出信号是病毒有效复制所必需的
DOI：
10.1128/jvi.06586-11
复制
发表时间：
2012-05-01
影响因子：
5.4
通讯作者：
Liu, Wenjun
中科院分区：
文献类型：
--
作者：
Cao, Shuai;Liu, Xiaoling;Liu, Wenjun
摘要甲型流感病毒基质1蛋白(M1)在病毒生命周期中穿梭于细胞质和细胞核之间，在病毒的复制、组装和萌发中发挥重要作用。在这里，一个富含亮氨酸的核出口信号(NES)被识别出来，专门用于M1蛋白的核出口。预测的NES序列命名为Flu-A-M1NES，在甲型流感病毒的所有序列中高度保守，但在B型或C型流感病毒的M1序列中没有发现类似的NES基序。通过将增强型绿色荧光蛋白(EGFP)-NES融合蛋白从细胞核转移到细胞质的能力，证明了Flu-A-M1 NES的生物学功能，而EGFP在细胞核和细胞质中的分布是均匀的。弱霉素B不能抑制EGFP-NES从细胞核到细胞质的转位。M1中的NES突变导致蛋白质在核内滞留，NEP在核内的积聚增加。事实上，正如被拯救的重组病毒所表明的那样，NES的突变损害了M1的核输出，并与野生型病毒的滴度相比显著降低了病毒滴度。在感染过程中，NES缺陷的M1蛋白保留在细胞核中，伴随着病毒RNPs(VRNPs)核输出效率的降低。总而言之，M1核出口特别依赖于流感-A-M1NES，对甲型流感病毒复制至关重要。
ABSTRACT The influenza A virus matrix 1 protein (M1) shuttles between the cytoplasm and the nucleus during the viral life cycle and plays an important role in the replication, assembly, and budding of viruses. Here, a leucine-rich nuclear export signal (NES) was identified specifically for the nuclear export of the M1 protein. The predicted NES, designated the Flu-A-M1 NES, is highly conserved among all sequences from the influenza A virus subtype, but no similar NES motifs are found in the M1 sequences of influenza B or C viruses. The biological function of the Flu-A-M1 NES was demonstrated by its ability to translocate an enhanced green fluorescent protein (EGFP)-NES fusion protein from the nucleus to the cytoplasm in transfected cells, compared to the even nuclear and cytoplasmic distribution of EGFP. The translocation of EGFP-NES from the nucleus to the cytoplasm was not inhibited by leptomycin B. NES mutations in M1 caused a nuclear retention of the protein and an increased nuclear accumulation of NEP during transfection. Indeed, as shown by rescued recombinant viruses, the mutation of the NES impaired the nuclear export of M1 and significantly reduced the virus titer compared to titers of wild-type viruses. The NES-defective M1 protein was retained in the nucleus during infection, accompanied by a lowered efficiency of the nuclear export of viral RNPs (vRNPs). In conclusion, M1 nuclear export was specifically dependent on the Flu-A-M1 NES and critical for influenza A virus replication.