Abstract
Many viruses use their host’s cellular machinery to regulate the functions of viral proteins. The phosphorylation of viral proteins is known to play a role in genome transcription and replication in paramyxoviruses. The paramyxovirus nucleoprotein (N), the most abundant protein in infected cells, is a component of the N–RNA complex and supports the transcription and replication of virus mRNA and genomic RNA. Recently, we reported that the phosphorylation of measles virus N is involved in the regulation of viral RNA synthesis. In this study, we report a rapid turnover of phosphorylation in the Nipah virus N (NiV-N). The phosphorylated NiV-N was hardly detectable in steady-state cells, but was detected after inhibition of cellular protein phosphatases. We identified a phosphorylated serine residue at Ser451 of NiV-N by peptide mass fingerprinting by electrospray ionization–quadrupole time-of-flight mass spectrometry. In the NiV minigenome assay, using luciferase as a reporter gene, the substitution of Ser451 for alanine in NiV-N resulted in a reduction in luciferase activity of approximately 45 % compared with the wild-type protein. Furthermore, the substitution of Ser451 for glutamic acid, which mimics a phosphoserine, led to a more significant decrease in luciferase activity – approximately 81 %. Northern blot analysis showed that both virus transcription and replication were reduced by these mutations. These results suggest that a rapid turnover of the phosphorylation of NiV-N plays an important role in virus transcription and replication.
Highlights
Nipah virus (NiV) is a recently emerged zoonotic virus that causes encephalitic and respiratory illness in humans and livestock, with a high mortality rate (40–70 %) in humans (Chua et al, 2000; WHO, 2004)
It has been reported that phosphorylation of the P protein at Ser54 of the human respiratory syncytial virus (HRSV), another member of the family Paramyxoviridae, is detected only by inhibition of cellular protein phosphatases, due to its immediate dephosphorylation (Asenjo et al, 2005)
To confirm whether Nipah virus N (NiV-N) is dephosphorylated immediately, 32P-labelling experiments were performed in the presence of okadaic acid (OKA), an inhibitor of cellular protein phosphatases
Summary
Nipah virus (NiV) is a recently emerged zoonotic virus that causes encephalitic and respiratory illness in humans and livestock, with a high mortality rate (40–70 %) in humans (Chua et al, 2000; WHO, 2004). NiV is a negative-stranded, ssRNA virus that belongs to the genus Henipavirus in the family Paramyxoviridae (Mayo, 2002a, b) and is composed of six structural proteins: nucleoprotein (N), phosphoprotein (P), matrix protein (M), fusion protein (F), glycoprotein (G) and large protein (L). The N protein encapsidates the genomic RNA and forms a nucleocapsid. This serves as a template for virus. The N-terminal 80 % of the protein forms a globular body, whereas the C-terminal 20 % appears to be a tail extending from the N-terminal body (Lamb & Parks, 2006). Measles virus (MV), which belongs to the genus Morbillivirus, has a well-characterized N protein. MV-N-CORE contains all of the necessary components for self-assembly and RNA binding, as N proteins that are composed only of the core
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
