4WSA: Crystal Structure Of Influenza B Polymerase Bound To The Vrna Promoter (flub1 Form)

Influenza virus polymerase uses a capped primer, derived by 'cap-snatching' from host pre-messenger RNA, to transcribe its RNA genome into mRNA and a stuttering mechanism to generate the poly(A) tail. By contrast, genome replication is unprimed and generates exact full-length copies of the template. Here we use crystal structures of bat influenza A and human influenza B polymerases (FluA and FluB), bound to the viral RNA promoter, to give mechanistic insight into these distinct processes. In the FluA structure, a loop analogous to the priming loop of flavivirus polymerases suggests that influenza could initiate unprimed template replication by a similar mechanism. Comparing the FluA and FluB structures suggests that cap-snatching involves in situ rotation of the PB2 cap-binding domain to direct the capped primer first towards the endonuclease and then into the polymerase active site. The polymerase probably undergoes considerable conformational changes to convert the observed pre-initiation state into the active initiation and elongation states.
PDB ID: 4WSADownload
MMDB ID: 124943
PDB Deposition Date: 2014/10/26
Updated in MMDB: 2014/12
Experimental Method:
x-ray diffraction
Resolution: 3.4  Å
Source Organism:
Influenza B virus (B/Memphis/13/2003)
Similar Structures:
Biological Unit for 4WSA: pentameric; determined by author and by software (PISA)
Molecular Components in 4WSA
Label Count Molecule
Proteins (3 molecules)
Molecule annotation
RNA-directed RNA Polymerase Catalytic Subunit
Molecule annotation
Molecule annotation
Nucleotides(2 molecules)
Influenza B Vrna Promoter 3' END
Molecule annotation
Influenza B Vrna Promoter 5' END
Molecule annotation
* Click molecule labels to explore molecular sequence information.

Citing MMDB