ORF7b

From Wikipedia, the free encyclopedia
Betacoronavirus NS7B protein
Identifiers
SymbolbCoV_NS7B
PfamPF11395
InterProIPR021532

ORF7b is a gene found in coronaviruses of the genus Betacoronavirus, which expresses the accessory protein Betacoronavirus NS7b protein.[1] It is a short, highly hydrophobic transmembrane protein of unknown function.[1][2]

Structure[]

ORF7b protein is a transmembrane protein with a single transmembrane helix whose membrane topology orients the C-terminus in the cytosol.[1] In SARS-CoV, it is 44 amino acid residues and in SARS-CoV-2 it is 43 residues, with about 85% sequence identity.[2]

Expression and localization[]

ORF7b is an overlapping gene that overlaps ORF7a.[3] The protein is probably expressed from subgenomic RNA through leaky scanning.[1] In SARS-CoV, it is localized to the Golgi apparatus, which requires the transmembrane helix sequence.[1][4] In SARS-CoV-2, it has been reported to associate with the endoplasmic reticulum.[5]

Function[]

The function of the ORF7b protein is not well characterized. It is not essential for viral replication,[1][3] though there is inconsistent evidence from studies of SARS-CoV on whether its deletion affects replication.[1][6] In SARS-CoV, it has been identified incorporating into virions, suggesting it is a minor viral structural protein.[1][7] A SARS-CoV-2 variant with a deletion mutation in the ORF7b region, resulting in a fusion protein between ORF7b and ORF8, has been identified, of unclear significance.[2][8]

References[]

  1. ^ a b c d e f g h Liu, DX; Fung, TS; Chong, KK; Shukla, A; Hilgenfeld, R (September 2014). "Accessory proteins of SARS-CoV and other coronaviruses". Antiviral Research. 109: 97–109. doi:10.1016/j.antiviral.2014.06.013. PMC 7113789. PMID 24995382.
  2. ^ a b c Redondo, Natalia; Zaldívar-López, Sara; Garrido, Juan J.; Montoya, Maria (7 July 2021). "SARS-CoV-2 Accessory Proteins in Viral Pathogenesis: Knowns and Unknowns". Frontiers in Immunology. 12: 708264. doi:10.3389/fimmu.2021.708264. hdl:10261/249329. PMC 8293742. PMID 34305949.
  3. ^ a b Pekosz, Andrew; Schaecher, Scott R.; Diamond, Michael S.; Fremont, Daved H.; Sims, Amy C.; Baric, Ralph S. (2006). "Structure, Expression, and Intracellular Localization of the SARS-CoV Accessory Proteins 7a and 7b". The Nidoviruses. Advances in Experimental Medicine and Biology. 581: 115–120. doi:10.1007/978-0-387-33012-9_20. ISBN 978-0-387-26202-4. PMC 7123408. PMID 17037516.
  4. ^ Schaecher, Scott R.; Diamond, Michael S.; Pekosz, Andrew (October 2008). "The Transmembrane Domain of the Severe Acute Respiratory Syndrome Coronavirus ORF7b Protein Is Necessary and Sufficient for Its Retention in the Golgi Complex". Journal of Virology. 82 (19): 9477–9491. doi:10.1128/JVI.00784-08. PMC 2546951. PMID 18632859.
  5. ^ Zhang, Jing; Cruz-cosme, Ruth; Zhuang, Meng-Wei; Liu, Dongxiao; Liu, Yuan; Teng, Shaolei; Wang, Pei-Hui; Tang, Qiyi (December 2020). "A systemic and molecular study of subcellular localization of SARS-CoV-2 proteins". Signal Transduction and Targeted Therapy. 5 (1): 269. doi:10.1038/s41392-020-00372-8. PMC 7670843. PMID 33203855.
  6. ^ McBride, Ruth; Fielding, Burtram (7 November 2012). "The Role of Severe Acute Respiratory Syndrome (SARS)-Coronavirus Accessory Proteins in Virus Pathogenesis". Viruses. 4 (11): 2902–2923. doi:10.3390/v4112902. PMC 3509677. PMID 23202509.
  7. ^ Schaecher, Scott R.; Mackenzie, Jason M.; Pekosz, Andrew (15 January 2007). "The ORF7b Protein of Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) Is Expressed in Virus-Infected Cells and Incorporated into SARS-CoV Particles". Journal of Virology. 81 (2): 718–731. doi:10.1128/JVI.01691-06. PMC 1797472. PMID 17079322.
  8. ^ Su, Yvonne C. F.; Anderson, Danielle E.; Young, Barnaby E.; Linster, Martin; Zhu, Feng; Jayakumar, Jayanthi; Zhuang, Yan; Kalimuddin, Shirin; Low, Jenny G. H.; Tan, Chee Wah; Chia, Wan Ni; Mak, Tze Minn; Octavia, Sophie; Chavatte, Jean-Marc; Lee, Raphael T. C.; Pada, Surinder; Tan, Seow Yen; Sun, Louisa; Yan, Gabriel Z.; Maurer-Stroh, Sebastian; Mendenhall, Ian H.; Leo, Yee-Sin; Lye, David Chien; Wang, Lin-Fa; Smith, Gavin J. D. (25 August 2020). "Discovery and Genomic Characterization of a 382-Nucleotide Deletion in ORF7b and ORF8 during the Early Evolution of SARS-CoV-2". mBio. 11 (4). doi:10.1128/mBio.01610-20. hdl:11343/277716. PMC 7374062. PMID 32694143.
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