The first step of transcription for some negative, single-stranded RNA viruses is cap snatching, in which the first 10 to 20 residues of a host cell RNA are removed (snatched) and used as the 5′ cap and primer to initiate the synthesis of the nascent viral mRNA.[1] The viral RNA-dependent RNA polymerase (RdRp) can then proceed to transcribe positive-sense viral mRNA using the negative-sense viral RNA as a template. Cap-snatching also explains why some viral mRNA have 5’ terminal extensions of 10-20 nucleotides that are not encoded for in the genome. Examples of viruses that engage in cap-snatching include influenza viruses (Orthomyxoviridae), Lassa virus (Arenaviridae), hantaan virus (Hantaviridae) and rift valley fever virus (Phenuiviridae). Most viruses snatch 15-20 nucleotides except for the families Arenaviridae and Nairoviridae and the genus Thogotovirus (Orthomyxoviridae) which use a shorter strand.[2]
In the influenza virus, cap snatching occurs in the nucleus of the cell. The cap snatching endonuclease function is contained in the PA subunit of the RNA polymerase.[3]
In Arenaviridae and Bunyavirales, cap-snatching takes place in the cytoplasm.[4]
- ^ Decroly, E; Canard, B (June 2017). "Biochemical principles and inhibitors to interfere with viral capping pathways". Current Opinion in Virology. 24: 87–96. doi:10.1016/j.coviro.2017.04.003. PMC 7185569. PMID 28527860.
- ^ Decroly, Etienne; Ferron, François; Lescar, Julien; Canard, Bruno (2011-12-05). "Conventional and unconventional mechanisms for capping viral mRNA". Nature Reviews. Microbiology. 10 (1): 51–65. doi:10.1038/nrmicro2675. ISSN 1740-1534. PMC 7097100. PMID 22138959.
- ^ Dias, Alexandre; Bouvier, Denis; Crépin, Thibaut; McCarthy, Andrew A.; Hart, Darren J.; Baudin, Florence; Cusack, Stephen; Ruigrok, Rob W. H. (2009-04-16). "The cap-snatching endonuclease of influenza virus polymerase resides in the PA subunit". Nature. 458 (7240): 914–918. Bibcode:2009Natur.458..914D. doi:10.1038/nature07745. ISSN 1476-4687. PMID 19194459. S2CID 4421958.
- ^ "Cap snatching ~ ViralZone page". viralzone.expasy.org. Retrieved 2019-12-05.