Disease relevance of N

• The nucleocapsid protein of coronavirus infectious bronchitis virus: crystal structure of its N-terminal domain and multimerization properties [1].
• A model for coronavirus shell formation is proposed in which dimerization of the C-terminal domain of IBV-N leads to oligomerization of the IBV-nucleocapsid protein and viral RNA condensation [1].
• Interactions between N proteins and RNA are thus crucial for the assembly of infectious virus particles [1].
• Molecular modelling, using the solution structure of severe acute respiratory (SARS) coronavirus N-protein, revealed that this motif is available for interaction with cellular factors which may mediate nucleolar localization [2].
• The nucleocapsid (N) gene of turkey coronavirus (TCV) was amplified by reverse transcriptase-polymerase chain reaction, cloned, and expressed in the baculovirus expression system [3].

High impact information on N

• However, export of N protein from the nucleus/nucleolus was not inhibited by leptomycin B treatment, indicating that N protein nuclear export is independent of the CRM1-mediated export pathway [4].
• Conserved among all coronaviruses are four structural proteins: the matrix (M), small envelope (E), and spike (S) proteins that are embedded in the viral membrane and the nucleocapsid phosphoprotein (N), which exists in a ribonucleoprotein complex in the lumen [5].
• The N protein is a highly immunogenic phosphoprotein also implicated in viral genome replication and in modulating cell signaling pathways [6].
• The carboxyl-terminal 120-residue polypeptide of infectious bronchitis virus nucleocapsid induces cytotoxic T lymphocytes and protects chickens from acute infection [7].
• Effector cells for CTL assays were collected from chickens infected with the Gray strain of IBV or inoculated with a DNA plasmid encoding nucleocapsid proteins [7].

Chemical compound and disease context of N

• Cache Valley virus N expressed with a histidine tag, bovine serum albumin, and the basic lysozyme protein did not shift the IBV RNA [8].
• The cELISA utilized a recombinant baculovirus (Autographa californica nuclear polyhedrosis virus)-expressed TCV nucleocapsid (N) protein and biotin-labeled TCV N protein-specific monoclonal antibody [9].
• The surface projections (peplomers) of avian infectious bronchitis virus (IBV) strain M41 have been separated from the nucleocapsid (N) and matrix (M) proteins by sedimentation in a sucrose gradient after virus disruption by the non-ionic detergent Nonidet P40 [10].
• Infectious bronchitis virus nucleocapsid protein interactions with the 3' untranslated region of genomic RNA depend on uridylate bases [11].

Biological context of N

• The genome position and size of this predicted polypeptide are consistent with it being the gene for the nucleocapsid protein [12].
• Phylogenetic analysis based on the deduced amino acid sequences of S, M, or N protein demonstrated that TCoV was clustered within the same genomic lineage as the IBV strains while all the other mammalian coronaviruses were grouped into separate clusters corresponding to antigenic groups I or II [13].
• N-terminal sequencing of [3H]leucine-labelled IBV-Beaudette membrane (M) polypeptide showed leucine residues at positions 8, 16 and 22 from the N-terminus; these results confirm the open reading frame identified by M.E.G. Boursnell et al [14].
• The binding site in the amino region of N was either not present or only partially present in the first 91 residues because no interaction with RNA was observed with the polypeptide incorporating these residues [8].
• The 3' untranslated region after the N gene of one strain was partially deleted after attenuation, and might be correlated with virulence [15].

Anatomical context of N

• The N protein was expressed under control of the vaccinia virus promoter P7.5 in chicken embryo fibroblast cell cultures as seen in immunofluorescence assay and in rFPV-inoculated specific-pathogen-free (SPF) chickens by detecting antibodies with enzyme-linked immunosorbent assay (ELISA) [16].
• Alanine substitution of either Arg-76 or Tyr-94 in the N-terminal domain of IBV N protein led to a significant decrease in its RNA-binding activity and a total loss of the infectivity of the viral RNA to Vero cells [17].
• Both hybridomas selectively recognized the internal nucleocapsid protein [18].
• Localization of a T-cell epitope within the nucleocapsid protein of avian coronavirus [19].
• In mice, a lymphocyte proliferative response and a delayed-type hypersensitivity reaction to IBV were induced upon immunization with this nucleocapsid protein [20].

Associations of N with chemical compounds

• One MAb (MAb 5) was directed against an epitope on the S1 subunit of the peplomer, another (MAb 2) against an epitope on the M glycoprotein and eight MAbs (MAbs 1, 7, 9, 16, 24, 26, 27 and 51) were directed against seven non-overlapping epitopes on the N protein [21].
• In order to identify domains in the N protein that bind to RNA, the whole protein (409 amino acids) and six overlapping fragments were expressed as fusion polypeptides with six histidine-tags [8].
• The residues identified and their positions relative to the N-terminus of S2 were: serine, 13; valine, 6, 12; leucine, none in the first 20 residues; isoleucine, 2, 19 [14].
• To locate the N-terminus of S2 we have performed partial amino acid sequencing on S2 from IBV-Beaudette labelled with [3H]serine and from the related strain labelled with [3H]valine, leucine and isoleucine [14].
• In contrast, mutation of amino acid Gln-74 to an alanine, which does not affect the binding activity of the N-terminal domain, showed minimal, if any, detrimental effect on the infectivity of IBV [17].

Analytical, diagnostic and therapeutic context of N

• A Saccharomyces cerevisiae-expressed nucleocapsid (N) polypeptide of the M41 strain of infectious bronchitis virus (IBV) was used as antigen in a recombinant yeast-expressed N protein-based enzyme-linked immunosorbent assay (Y-N-ELISA) [22].
• The sequence of the N gene was different between serologically indistinguishable IBV strains and may be a valuable tool in epidemiologic studies [23].
• The interaction of N protein with viral RNA was investigated using circular dichroism and surface plasmon resonance [24].
• This genetic relation to the vaccine virus was also confirmed by N gene sequence analysis [25].
• The purpose of this study is to investigate the molecular epidemiology of IBV in Taiwan. An old IBV strain isolated in 1964 and another 31 strains isolated from 1991 to 2003 were selected for N-terminal S1 gene analysis [26].

References