Characterization of N protein self-association in coronavirus ribonucleoprotein complexes

Abstract

Mouse hepatitis virus (MHV) nucleocapsid (N) protein binds to the large, single-stranded, positive-sense viral genomic RNA to form a helical nucleocapsid structure in mature virions. In addition N protein binds the intracellular form of the genomic RNA, all of the MHV subgenomic mRNAs, and expressed non-MHV RNA transcripts to form ribonucleoprotein (RNP) complexes in infected cells. Among the intracellular viral RNP complexes, only the genomic RNP complex is packaged into virus particles. The present study demonstrated that N protein in the MHV virion nucleocapsid and in the intracellular genome-length RNP complex that bound to viral envelope M protein was tightly self-associated such that its association was retained even after extensive RNase A-treatment of the RNP complexes. The RNase A-resistant tight N protein association in the virion nucleocapsid was not mediated by an intermolecular disulfide bridge between N proteins. In contrast, N protein association in the majority of the intracellular RNP complexes was susceptible to RNase A-treatment. Because the RNP complexes that specifically interact with the M protein are selectively packaged into MHV particles, the present data suggested that there was a distinct difference between N protein association in viral genomic RNP complexes that undergo packaging into virus particles and the subgenomic RNP complexes that are not packaged into MHV particles.

Severe acute respiratory syndrome coronavirus nucleocapsid protein does not modulate transcription of the human FGL2 gene

“…As such, both proteins are capable of multimerization and RNA binding (Narayanan et al, 2003;Luo et al, 2005;Zú ñiga et al, 2007). In addition, both proteins have gene regulatory activity and can repress IFN production (Kopecky-Bromberg et al, 2007;Ye et al, 2007).…”

“…The coronavirus nucleocapsid (N) protein is a relatively conserved structural protein that binds genomic RNA and plays an important role in viral RNA synthesis, viral assembly and formation of the RNA replication complex (Narayanan et al, 2003;Almazán et al, 2004). Intracellularly, coronavirus N protein localizes to the cytoplasm, in which it interacts with M protein to form an icosahedral core (Hurst et al, 2005).…”

Subcellular Localization of SARS-CoV Structural Proteins

“…[3][4][5] The N protein is a multifunctional phosphoprotein that encapsidates the viral genome and plays a role in virus assembly. 6,7 N also appears to be involved in viral RNA replication and/or transcription. 8,9 The aim in this study was to provide a comprehensive view of the subcellular localization of the main SARS-CoV structural proteins.…”

Recombinant Protein-Based Assays for Detection of Antibodies to Severe Acute Respiratory Syndrome Coronavirus Spike and Nucleocapsid Proteins

“…Since the end of the SARS outbreak, there have been 17 identified SARS-associated coronavirus (SARS-CoV) infections, 6 from direct laboratory exposure, 1 of which resulted in community transmission to seven individuals, and 4 sporadic, community-acquired infections (9). Since additional cases may occur and could, if undetected, quickly lead to another global outbreak, it is important to continue to improve our ability to reliably monitor SARS-CoV infections (3,16,18).As with other coronaviruses, the spike (S) and nucleocapsid (N) proteins are abundantly expressed during virus infection and are most effective among the coronavirus structural proteins at inducing antibody responses (10,14,15,23). Previous studies have demonstrated the utility of anti-N and anti-S proteins in the diagnosis of SARS-CoV infections (2,5,12,21).…”

“…As with other coronaviruses, the spike (S) and nucleocapsid (N) proteins are abundantly expressed during virus infection and are most effective among the coronavirus structural proteins at inducing antibody responses (10,14,15,23). Previous studies have demonstrated the utility of anti-N and anti-S proteins in the diagnosis of SARS-CoV infections (2,5,12,21).…”