Related Research Articles
Rotavirus is a genus of double-stranded RNA viruses in the family Reoviridae. Rotaviruses are the most common cause of diarrhoeal disease among infants and young children. Nearly every child in the world is infected with a rotavirus at least once by the age of five. Immunity develops with each infection, so subsequent infections are less severe. Adults are rarely affected. There are nine species of the genus, referred to as A, B, C, D, F, G, H, I and J. Rotavirus A, the most common species, causes more than 90% of rotavirus infections in humans.
Coronaviruses are a group of related RNA viruses that cause diseases in mammals and birds. In humans and birds, they cause respiratory tract infections that can range from mild to lethal. Mild illnesses in humans include some cases of the common cold, while more lethal varieties can cause SARS, MERS and COVID-19, which is causing the ongoing pandemic. In cows and pigs they cause diarrhea, while in mice they cause hepatitis and encephalomyelitis.
Severe acute respiratory syndrome–related coronavirus is a species of virus consisting of many known strains phylogenetically related to severe acute respiratory syndrome coronavirus 1 (SARS-CoV-1) that have been shown to possess the capability to infect humans, bats, and certain other mammals. These enveloped, positive-sense single-stranded RNA viruses enter host cells by binding to the angiotensin-converting enzyme 2 (ACE2) receptor. The SARSr-CoV species is a member of the genus Betacoronavirus and of the subgenus Sarbecovirus.
A viral protein is both a component and a product of a virus. Viral proteins are grouped according to their functions, and groups of viral proteins include structural proteins, nonstructural proteins, regulatory proteins, and accessory proteins. Viruses are non-living and do not have the means to reproduce on their own, instead depending on their host cell's resources in order to reproduce. Thus, viruses do not code for many of their own viral proteins, and instead use the host cell's machinery to produce the viral proteins they require for replication.
The Coronavirus packaging signal is a conserved cis-regulatory element found in Betacoronavirus. It has an important role in regulating the packaging of the viral genome into the capsid. As part of the viral life cycle, within the infected cell, the viral genome becomes associated with viral proteins and assembles into new infective progeny viruses. This process is called packaging and is vital for viral replication.
Rotavirus translation, the process of translating mRNA into proteins, occurs in a different way in Rotaviruses. Unlike the vast majority of cellular proteins in other organisms, in Rotaviruses the proteins are translated from capped but nonpolyadenylated mRNAs. The viral nonstructural protein NSP3 specifically binds the 3'-end consensus sequence of viral mRNAs and interacts with the eukaryotic translation initiation factor eIF4G. The Rotavirus replication cycle occurs entirely in the cytoplasm. Upon virus entry, the viral transcriptase synthesizes capped but nonpolyadenylated mRNA The viral mRNAs bear 5' and 3' untranslated regions (UTR) of variable length and are flanked by two different sequences common to all genes.
RoXaN also known as ZC3H7B, is a protein that in humans is encoded by the ZC3H7B gene. RoXaN is a protein that contains tetratricopeptide repeat and leucine-aspartate repeat as well as zinc finger domains. This protein also interacts with the rotavirus non-structural protein NSP3.
In virology, a nonstructural protein is a protein encoded by a virus but that is not part of the viral particle. They typically include the various enzymes and transcription factors the virus uses to replicate itself, such as a viral protease, an RNA replicase or other template-directed polymerases, and some means to control the host.
NSP1 (NS53), the product of rotavirus gene 5, is a nonstructural RNA-binding protein that contains a cysteine-rich region and is a component of early replication intermediates. RNA-folding predictions suggest that this region of the NSP1 mRNA can interact with itself, producing a stem-loop structure similar to that found near the 5'-terminus of the NSP1 mRNA.
NSP2 (NS35), is a rotavirus nonstructural RNA-binding protein that accumulates in cytoplasmic inclusions (viroplasms) and is required for genome replication. NSP2 is closely associated in vivo with the viral replicase. The non-structural protein NSP5 plays a role in the structure of viroplasms mediated by its interaction with NSP2.
Rotavirus protein NSP3 (NS34) is bound to the 3' end consensus sequence of viral mRNAs in infected cells.
The rotavirus nonstructural protein NSP4 was the first viral enterotoxin discovered. It is a viroporin and induces diarrhea and causes Ca2+-dependent transepithelial secretion.
NSP5 encoded by genome segment 11 of group A rotaviruses. In virus-infected cells NSP5 accumulates in the viroplasms. NSP5 has been shown to be autophosphorylated. Interaction of NSP5 with NSP2 was also demonstrated. In rotavirus-infected cells, the non-structural proteins NSP5 and NSP2 localize in complexes called viroplasms, where replication and assembly occur and they can drive the formation of viroplasm-like structures in the absence of other rotaviral proteins and rotavirus replication.
VAMP-Associated Protein A is a protein that in humans is encoded by the VAPA gene. Together with VAPB and VAPC it forms the VAP protein family. They are integral endoplasmic reticulum membrane proteins of the type II and are ubiquitous among eukaryotes.
A viral structural protein is a viral protein that is a structural component of the mature virus.
Viroporins are small and usually hydrophobic multifunctional viral proteins that modify cellular membranes, thereby facilitating virus release from infected cells. Viroporins are capable of assembling into oligomeric ion channels or pores in the host cell's membrane, rendering it more permeable and thus facilitating the exit of virions from the cell. Many viroporins also have additional effects on cellular metabolism and homeostasis mediated by protein-protein interactions with host cell proteins. Viroporins are not necessarily essential for viral replication, but do enhance growth rates. They are found in a variety of viral genomes but are particularly common in RNA viruses. Many viruses that cause human disease express viroporins. These viruses include hepatitis C virus, HIV-1, influenza A virus, poliovirus, respiratory syncytial virus, and SARS-CoV.
Positive-strand RNA viruses are a group of related viruses that have positive-sense, single-stranded genomes made of ribonucleic acid. The positive-sense genome can act as messenger RNA (mRNA) and can be directly translated into viral proteins by the host cell's ribosomes. Positive-strand RNA viruses encode an RNA-dependent RNA polymerase (RdRp) which is used during replication of the genome to synthesize a negative-sense antigenome that is then used as a template to create a new positive-sense viral genome.
The envelope (E) protein is the smallest and least well-characterized of the four major structural proteins found in coronavirus virions. It is an integral membrane protein less than 110 amino acid residues long; in SARS-CoV-2, the causative agent of Covid-19, the E protein is 75 residues long. Although it is not necessarily essential for viral replication, absence of the E protein may produce abnormally assembled viral capsids or reduced replication. E is a multifunctional protein and, in addition to its role as a structural protein in the viral capsid, it is thought to be involved in viral assembly, likely functions as a viroporin, and is involved in viral pathogenesis.
ORF1ab refers collectively to two open reading frames (ORFs), ORF1a and ORF1b, that are conserved in the genomes of nidoviruses, a group of viruses that includes coronaviruses. The genes express large polyproteins that undergo proteolysis to form several nonstructural proteins with various functions in the viral life cycle, including proteases and the components of the replicase-transcriptase complex (RTC). Together the two ORFs are sometimes referred to as the replicase gene. They are related by a programmed ribosomal frameshift that allows the ribosome to continue translating past the stop codon at the end of ORF1a, in a -1 reading frame. The resulting polyproteins are known as pp1a and pp1ab.
The nidoviral papain-like protease is a papain-like protease protein domain encoded in the genomes of nidoviruses. It is expressed as part of a large polyprotein from the ORF1a gene and has cysteine protease enzymatic activity responsible for proteolytic cleavage of some of the N-terminal viral nonstructural proteins within the polyprotein. A second protease also encoded by ORF1a, called the 3C-like protease or main protease, is responsible for the majority of further cleavages. Coronaviruses have one or two papain-like protease domains; in SARS-CoV and SARS-CoV-2, one PLPro domain is located in coronavirus nonstructural protein 3 (nsp3). Arteriviruses have two to three PLP domains. In addition to their protease activity, PLP domains function as deubiquitinating enzymes (DUBs) that can cleave the isopeptide bond found in ubiquitin chains. They are also "deISGylating" enzymes that remove the ubiquitin-like domain interferon-stimulated gene 15 (ISG15) from cellular proteins. These activities are likely responsible for antagonizing the activity of the host innate immune system. Because they are essential for viral replication, papain-like protease domains are considered drug targets for the development of antiviral drugs against human pathogens such as MERS-CoV, SARS-CoV, and SARS-CoV-2.
References
- ↑ Yadav, Rohitash; Chaudhary, Jitendra Kumar; Jain, Neeraj; Chaudhary, Pankaj Kumar; Khanra, Supriya; Dhamija, Puneet; Sharma, Ambika; Kumar, Ashish; Handu, Shailendra (2021-04-06). "Role of Structural and Non-Structural Proteins and Therapeutic Targets of SARS-CoV-2 for COVID-19". Cells. 10 (4): 821. doi:10.3390/cells10040821. ISSN 2073-4409.
- ↑ Komoto, Satoshi; Kanai, Yuta; Fukuda, Saori; Kugita, Masanori; Kawagishi, Takahiro; Ito, Naoto; Sugiyama, Makoto; Matsuura, Yoshiharu; Kobayashi, Takeshi; Taniguchi, Koki (November 2017). "Reverse Genetics System Demonstrates that Rotavirus Nonstructural Protein NSP6 Is Not Essential for Viral Replication in Cell Culture". Journal of Virology. 91 (21). doi:10.1128/JVI.00695-17. ISSN 0022-538X.
- ↑ Baliji, Surendranath; Cammer, Stephen A; Sobral, Bruno; Baker, Susan C (2009-07-01). "Detection of nonstructural protein 6 in murine coronavirus-infected cells and analysis of the transmembrane topology by using bioinformatics and molecular approaches". Journal of virology. 83 (13): 6957–6962. doi:10.1128/jvi.00254-09. ISSN 1098-5514. PMC 2698535 . PMID 19386712.
- ↑ Rainsford, Edward W.; McCrae, Malcolm A. (2007-12-01). "Characterization of the NSP6 protein product of rotavirus gene 11". Virus Research. 130 (1): 193–201. doi:10.1016/j.virusres.2007.06.011. ISSN 0168-1702.
- ↑ Ricciardi, Simona; Guarino, Andrea Maria; Giaquinto, Laura; Polishchuk, Elena V.; Santoro, Michele; Di Tullio, Giuseppe; Wilson, Cathal; Panariello, Francesco; Soares, Vinicius C.; Dias, Suelen S. G.; Santos, Julia C.; Souza, Thiago M. L.; Fusco, Giovanna; Viscardi, Maurizio; Brandi, Sergio (June 2022). "The role of NSP6 in the biogenesis of the SARS-CoV-2 replication organelle". Nature. 606 (7915): 761–768. doi:10.1038/s41586-022-04835-6. ISSN 1476-4687. PMC 7612910 . PMID 35551511.
- ↑ Benvenuto, Domenico; Angeletti, Silvia; Giovanetti, Marta; Bianchi, Martina; Pascarella, Stefano; Cauda, Roberto; Ciccozzi, Massimo; Cassone, Antonio (July 2020). "Evolutionary analysis of SARS-CoV-2: how mutation of Non-Structural Protein 6 (NSP6) could affect viral autophagy". Journal of Infection. 81 (1): e24–e27. doi:10.1016/j.jinf.2020.03.058. ISSN 0163-4453.
- ↑ Cottam, Eleanor M; Whelband, Matthew C; Wileman, Thomas (2014-08-01). "Coronavirus NSP6 restricts autophagosome expansion". Autophagy. 10 (8): 1426–1441. doi:10.4161/auto.29309. ISSN 1554-8627. PMC 4203519 . PMID 24991833.
 | This molecular or cell biology article is a stub. You can help Wikipedia by expanding it. |
 | This cell biology article is a stub. You can help Wikipedia by expanding it. |
 | This enzyme-related article is a stub. You can help Wikipedia by expanding it. |