Sandbox Reserved 1683: Difference between revisions

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Influenza A being comprised of negative-sense RNA means it cannot be immediately translated by the host, and instead the viral RNA must first be copied so that the complementary strand runs in the proper 5' to 3' direction.<ref>PMID:23009810</ref> Influenza A utilizes its viral polymerase to engage in cap-snatching in which it takes 5' capped RNA fragments from the host's capped RNAs.<ref>PMID:27396566</ref> Afterwards, the cap-binding domain rotates to insert the 3' end of the capped RNA into the active site, and NTPs enter through the entry channel as the polymerase constructs a strand complementary to the viral RNA.<ref>PMID:27396566</ref>
Influenza A being comprised of negative-sense RNA means it cannot be immediately translated by the host, and instead the viral RNA must first be copied so that the complementary strand runs in the proper 5' to 3' direction.<ref>PMID:23009810</ref> Influenza A utilizes its viral polymerase to engage in cap-snatching in which it takes 5' capped RNA fragments from the host's capped RNAs.<ref>PMID:27396566</ref> Afterwards, the cap-binding domain rotates to insert the 3' end of the capped RNA into the active site, and NTPs enter through the entry channel as the polymerase constructs a strand complementary to the viral RNA.<ref>PMID:27396566</ref>


Influenza A utilizes its trimer subunits to bind the template strand: the host capped RNA is bound by the PB2 cap-binding domain, followed by the cleavage of the PA/P3 endonuclease domain.<ref>PMID:27396566</ref> As mentioned before, the cap-binding domain then rotates allowing the insertion of the 3' end of the capped RNA, and then initiation begins once GTP is added to the 3' end of the capped primer which has become templated by the second residue in the viral RNA template.<ref>PMID:27396566</ref>
Influenza A uses its trimer subunits to bind the template strand: the host capped RNA is bound by the PB2 cap-binding domain, followed by the cleavage of the PA/P3 endonuclease domain.<ref>PMID:27396566</ref> As mentioned before, the cap-binding domain then rotates allowing the insertion of the 3' end of the capped RNA, and then initiation begins once GTP is added to the 3' end of the capped primer which has become templated by the second residue in the viral RNA template.<ref>PMID:27396566</ref>


Nucleotides are guided into the polymerase through the entry channel, which is made of highly conserved basic amino acids and consists of all three Influenza A RDRP subunits.<ref>PMID:27396566</ref> The priming loop is especially important, as it is a beta-hairpin that protrudes from the PB1 thumb domain and has the role of supporting the sugar-base of the initiating nucleotide and it contains <scene name='89/891373/Priming_loop/3'>conserved residues</scene> such as PRO651 and the catalytic ASP445-446.<ref>PMID:27396566</ref>
Nucleotides are guided into the polymerase through the entry channel, which is made of highly conserved basic amino acids and consists of all three Influenza A RDRP subunits.<ref>PMID:27396566</ref> The priming loop is especially important, as it is a beta-hairpin that protrudes from the PB1 thumb domain and has the role of supporting the sugar-base of the initiating nucleotide and it contains <scene name='89/891373/Priming_loop/3'>conserved residues</scene> such as PRO651 and the catalytic ASP445-446.<ref>PMID:27396566</ref>
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