Human coronavirus 229E papain-like proteases have overlapping specificities but distinct functions in viral replication.

Expression of the exceptionally large RNA genomes of CoVs involves multiple regulatory mechanisms, including extensive proteolytic processing of the large replicase polyproteins, pp1a and pp1ab, by two types of cysteine proteases: the chymotrypsin-like main protease and papain-like accessory proteases (PLpros). Here, we characterized the proteolytic processing of the human coronavirus 229E (HCoV-229E) amino-proximal pp1a/pp1ab region by two paralogous PLpro activities. Reverse-genetics data revealed that replacement of the PL2pro active-site cysteine was lethal.

Characterization of White bream virus reveals a novel genetic cluster of nidoviruses.

The order Nidovirales comprises viruses from the families Coronaviridae (genera Coronavirus and Torovirus), Roniviridae (genus Okavirus), and Arteriviridae (genus Arterivirus). In this study, we characterized White bream virus (WBV), a bacilliform plus-strand RNA virus isolated from fish. Analysis of the nucleotide sequence, organization, and expression of the 26.

Major genetic marker of nidoviruses encodes a replicative endoribonuclease.

Coronaviruses are important pathogens that cause acute respiratory diseases in humans. Replication of the approximately 30-kb positive-strand RNA genome of coronaviruses and discontinuous synthesis of an extensive set of subgenome-length RNAs (transcription) are mediated by the replicase-transcriptase, a barely characterized protein complex that comprises several cellular proteins and up to 16 viral subunits. The coronavirus replicase-transcriptase was recently predicted to contain RNA-processing enzymes that are extremely rare or absent in other RNA viruses.

Mechanisms and enzymes involved in SARS coronavirus genome expression.

A novel coronavirus is the causative agent of the current epidemic of severe acute respiratory syndrome (SARS). Coronaviruses are exceptionally large RNA viruses and employ complex regulatory mechanisms to express their genomes. Here, we determined the sequence of SARS coronavirus (SARS-CoV), isolate Frankfurt 1, and characterized key RNA elements and protein functions involved in viral genome expression.

The 3C-like proteinase of an invertebrate nidovirus links coronavirus and potyvirus homologs.

Gill-associated virus (GAV), a positive-stranded RNA virus of prawns, is the prototype of newly recognized taxa (genus Okavirus, family Roniviridae) within the order NIDOVIRALES: In this study, a putative GAV cysteine proteinase (3C-like proteinase [3CL(pro)]), which is predicted to be the key enzyme involved in processing of the GAV replicase polyprotein precursors, pp1a and pp1ab, was characterized. Comparative sequence analysis indicated that, like its coronavirus homologs, 3CL(pro) has a three-domain organization and is flanked by hydrophobic domains. The putative 3CL(pro) domain including flanking regions (pp1a residues 2793 to 3143) was fused to the Escherichia coli maltose-binding protein (MBP) and, when expressed in E.