Nuclear/nucleolar localization properties of C-terminal nucleocapsid protein of SARS coronavirus.
A novel coronavirus (CoV) has recently been identified as the aetiological agent of severe acute respiratory syndrome (SARS). Nucleocapsid (N) proteins of the Coronaviridae family have no discernable homology, but they share a common nucleolar-cytoplasmic distribution pattern. There are three putative nuclear localization signal (NLS) motifs present in the N. To determine the role of these putative NLSs in the intracellular localization of the SARS-CoV N, we performed a confocal microscopy analysis using rabbit anti-N antisera. In this report, we show that the wild type N was distributed mainly in the cytoplasm. The N-terminal of the N, which contains the NLS1 (aa38-44), was localized to the nucleus. The C-terminus of the N, which contains both NLS2 (aa257-265) and NLS3 (aa369-390) was localized to the cytoplasm and the nucleolus. Results derived from analysis of various deletion mutations show that the region containing amino acids 226-289 is able to mediate nucleolar localization. The deletion of two hydrophobic regions that flanked the NLS3 recovered its activity and localized to the nucleus. Furthermore, deletion of leucine rich region (220-LALLLLDRLNRL) resulted in the accumulation of N to the cytoplasm and nucleolus, and when fusing this peptide to EGFP localization was cytoplasmic, suggesting that the N may act as a shuttle protein. Differences in nuclear/nucleolar localization properties of N from other members of coronavirus family suggest a unique function for N, which may play an important role in the pathogenesis of SARS.
State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei Province 430072, PR China.
Khalid Amine
KA
Timani
Qingjiao
Q
Liao
Linbai
L
Ye
Yingchun
Y
Zeng
Jing
J
Liu
Yi
Y
Zheng
Li
L
Ye
Xiaojun
X
Yang
Kong
K
Lingbao
Jingrong
J
Gao
Ying
Y
Zhu
D000818:Animals; D002466:Cell Nucleolus / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism*; D002522:Chlorocebus aethiops; D000086462:Coronavirus Nucleocapsid Proteins; D005434:Flow Cytometry; D017353:Gene Deletion; D006801:Humans; D018613:Microscopy, Confocal; D019913:Nuclear Localization Signals; D019590:Nucleocapsid Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011817:Rabbits; D045473:Severe acute respiratory syndrome-related coronavirus / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D014162:Transfection; D014709:Vero Cells
D000086462:Coronavirus Nucleocapsid Proteins; D019913:Nuclear Localization Signals; D019590:Nucleocapsid Proteins