Capped RNA primer binding to influenza polymerase and implications for the mechanism of cap-binding inhibitors.
Nucleic Acids Res
; 46(2): 956-971, 2018 01 25.
Article
in En
| MEDLINE
| ID: mdl-29202182
ABSTRACT
Influenza polymerase uses short capped primers snatched from nascent Pol II transcripts to initiate transcription of viral mRNAs. Here we describe crystal structures of influenza A and B polymerase bound to a capped primer in a configuration consistent with transcription initiation ('priming state') and show by functional assays that conserved residues from both the PB2 midlink and cap-binding domains are important for positioning the capped RNA. In particular, mutation of PB2 Arg264, which interacts with the triphosphate linkage in the cap, significantly and specifically decreases cap-dependent transcription. We also compare the configuration of the midlink and cap-binding domains in the priming state with their very different relative arrangement (called the 'apo' state) in structures where the potent cap-binding inhibitor VX-787, or a close analogue, is bound. In the 'apo' state the inhibitor makes additional interactions to the midlink domain that increases its affinity beyond that to the cap-binding domain alone. The comparison suggests that the mechanism of resistance of certain mutations that allow virus to escape from VX-787, notably PB2 N510T, can only be rationalized if VX-787 has a dual mode of action, direct inhibition of capped RNA binding as well as stabilization of the transcriptionally inactive 'apo' state.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Viral Proteins
/
RNA Polymerase II
/
RNA
/
RNA Cap Analogs
/
RNA Caps
Limits:
Humans
Language:
En
Journal:
Nucleic Acids Res
Year:
2018
Type:
Article
Affiliation country:
France