ID   RDRP_I33A0              Reviewed;         757 AA.
AC   P03430;
DT   21-JUL-1986, integrated into UniProtKB/Swiss-Prot.
DT   21-JUL-1986, sequence version 1.
DT   10-JUN-2026, entry version 120.
DE   RecName: Full=RNA-directed RNA polymerase catalytic subunit {ECO:0000255|HAMAP-Rule:MF_04065};
DE            EC=2.7.7.48 {ECO:0000255|HAMAP-Rule:MF_04065};
DE   AltName: Full=Polymerase basic protein 1 {ECO:0000255|HAMAP-Rule:MF_04065};
DE            Short=PB1 {ECO:0000255|HAMAP-Rule:MF_04065};
DE   AltName: Full=RNA-directed RNA polymerase subunit P1 {ECO:0000255|HAMAP-Rule:MF_04065};
GN   Name=PB1 {ECO:0000255|HAMAP-Rule:MF_04065};
OS   Influenza A virus (strain A/Wilson-Smith/1933 H1N1) (Influenza A virus
OS   (strain A/WS/1933 H1N1)).
OC   Viruses; Riboviria; Orthornavirae; Negarnaviricota; Polyploviricotina;
OC   Insthoviricetes; Articulavirales; Orthomyxoviridae; Alphainfluenzavirus;
OC   Alphainfluenzavirus influenzae; Influenza A virus.
OX   NCBI_TaxID=381518;
OH   NCBI_TaxID=8782; Aves.
OH   NCBI_TaxID=9606; Homo sapiens (Human).
OH   NCBI_TaxID=9823; Sus scrofa (Pig).
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC RNA].
RX   PubMed=7143569; DOI=10.1128/jvi.44.1.321-329.1982;
RA   Sivasubramanian N., Nayak D.P.;
RT   "Sequence analysis of the polymerase 1 gene and the secondary structure
RT   prediction of polymerase 1 protein of human influenza virus A/WSN/33.";
RL   J. Virol. 44:321-329(1982).
RN   [2]
RP   NUCLEAR LOCALIZATION SIGNAL.
RX   PubMed=2196448; DOI=10.1128/mcb.10.8.4139-4145.1990;
RA   Nath S.T., Nayak D.P.;
RT   "Function of two discrete regions is required for nuclear localization of
RT   polymerase basic protein 1 of A/WSN/33 influenza virus (H1 N1).";
RL   Mol. Cell. Biol. 10:4139-4145(1990).
RN   [3]
RP   MUTAGENESIS OF ARG-233; LYS-235; ARG-238; ARG-239; ARG-249; PHE-251;
RP   PHE-254; SER-269; VAL-273; LYS-278 AND LYS-281.
RX   PubMed=16476991; DOI=10.1099/vir.0.81453-0;
RA   Jung T.E., Brownlee G.G.;
RT   "A new promoter-binding site in the PB1 subunit of the influenza A virus
RT   polymerase.";
RL   J. Gen. Virol. 87:679-688(2006).
CC   -!- FUNCTION: RNA-dependent RNA polymerase which is responsible for
CC       replication and transcription of virus RNA segments. The transcription
CC       of viral mRNAs occurs by a unique mechanism called cap-snatching. 5'
CC       methylated caps of cellular mRNAs are cleaved after 10-13 nucleotides
CC       by PA. In turn, these short capped RNAs are used as primers by PB1 for
CC       transcription of viral mRNAs. During virus replication, PB1 initiates
CC       RNA synthesis and copy vRNA into complementary RNA (cRNA) which in turn
CC       serves as a template for the production of more vRNAs.
CC       {ECO:0000255|HAMAP-Rule:MF_04065}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=RNA(n) + a ribonucleoside 5'-triphosphate = RNA(n+1) +
CC         diphosphate; Xref=Rhea:RHEA:21248, Rhea:RHEA-COMP:14527, Rhea:RHEA-
CC         COMP:17342, ChEBI:CHEBI:33019, ChEBI:CHEBI:61557, ChEBI:CHEBI:140395;
CC         EC=2.7.7.48; Evidence={ECO:0000255|HAMAP-Rule:MF_04065};
CC   -!- SUBUNIT: Influenza RNA polymerase is composed of three subunits: PB1,
CC       PB2 and PA. Interacts (via N-terminus) with PA (via C-terminus).
CC       Interacts (via C-terminus) with PB2 (via N-terminus); this interaction
CC       is essential for transcription initiation. Interacts (via C-terminus)
CC       with human PKP2 (via N-terminus); the interaction competitively
CC       inhibits the interaction between the RNA polymerase subunits PB1 and
CC       PB2 (By similarity). {ECO:0000250|UniProtKB:P03431, ECO:0000255|HAMAP-
CC       Rule:MF_04065}.
CC   -!- INTERACTION:
CC       P03430; P03427: PB2; NbExp=3; IntAct=EBI-8434155, EBI-8430745;
CC   -!- SUBCELLULAR LOCATION: Host nucleus {ECO:0000255|HAMAP-Rule:MF_04065}.
CC       Host cytoplasm {ECO:0000255|HAMAP-Rule:MF_04065}.
CC   -!- PTM: Phosphorylated by host PRKCA. {ECO:0000255|HAMAP-Rule:MF_04065}.
CC   -!- SIMILARITY: Belongs to the influenza viruses polymerase PB1 family.
CC       {ECO:0000255|HAMAP-Rule:MF_04065}.
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DR   EMBL; J02178; AAA43582.1; ALT_SEQ; Genomic_RNA.
DR   PIR; A04046; P1IV33.
DR   SMR; P03430; -.
DR   IntAct; P03430; 23.
DR   MINT; P03430; -.
DR   GO; GO:0030430; C:host cell cytoplasm; IEA:UniProtKB-SubCell.
DR   GO; GO:0042025; C:host cell nucleus; IDA:UniProtKB.
DR   GO; GO:0000166; F:nucleotide binding; IEA:UniProtKB-UniRule.
DR   GO; GO:0003723; F:RNA binding; IEA:InterPro.
DR   GO; GO:0003968; F:RNA-directed RNA polymerase activity; IEA:UniProtKB-UniRule.
DR   GO; GO:0006351; P:DNA-templated transcription; IEA:UniProtKB-UniRule.
DR   GO; GO:0039689; P:negative stranded viral RNA replication; IDA:UniProtKB.
DR   GO; GO:0039657; P:symbiont-mediated suppression of host gene expression; IEA:UniProtKB-KW.
DR   GO; GO:0039523; P:symbiont-mediated suppression of host mRNA transcription via inhibition of RNA polymerase II activity; IEA:UniProtKB-UniRule.
DR   GO; GO:0019083; P:viral transcription; IEA:UniProtKB-KW.
DR   Gene3D; 6.10.140.720; -; 1.
DR   HAMAP; MF_04065; INFV_RDRP; 1.
DR   InterPro; IPR007099; RNA-dir_pol_NSvirus.
DR   InterPro; IPR001407; RNA_pol_PB1_influenza.
DR   Pfam; PF00602; Flu_PB1; 1.
DR   PIRSF; PIRSF000827; RdRPol_OMV; 1.
DR   PROSITE; PS50525; RDRP_SSRNA_NEG_SEG; 1.
PE   1: Evidence at protein level;
KW   Eukaryotic host gene expression shutoff by virus;
KW   Eukaryotic host transcription shutoff by virus; Host cytoplasm;
KW   Host gene expression shutoff by virus; Host nucleus;
KW   Host-virus interaction; Inhibition of host RNA polymerase II by virus;
KW   Nucleotide-binding; Nucleotidyltransferase; Phosphoprotein;
KW   RNA-directed RNA polymerase; Transferase; Viral RNA replication;
KW   Viral transcription.
FT   CHAIN           1..757
FT                   /note="RNA-directed RNA polymerase catalytic subunit"
FT                   /id="PRO_0000078767"
FT   DOMAIN          286..483
FT                   /note="RdRp catalytic"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_04065"
FT   REGION          53..82
FT                   /note="Disordered"
FT                   /evidence="ECO:0000256|SAM:MobiDB-lite"
FT   REGION          249..256
FT                   /note="Promoter-binding site"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_04065"
FT   MOTIF           187..195
FT                   /note="Nuclear localization signal"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_04065,
FT                   ECO:0000269|PubMed:2196448"
FT   MOTIF           203..216
FT                   /note="Nuclear localization signal"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_04065,
FT                   ECO:0000269|PubMed:2196448"
FT   COMPBIAS        55..64
FT                   /note="Polar residues"
FT                   /evidence="ECO:0000256|SAM:MobiDB-lite"
FT   MUTAGEN         233
FT                   /note="R->A: Complete loss of RNA synthesis in vitro."
FT                   /evidence="ECO:0000269|PubMed:16476991"
FT   MUTAGEN         235
FT                   /note="K->A: Complete loss of RNA synthesis in vitro."
FT                   /evidence="ECO:0000269|PubMed:16476991"
FT   MUTAGEN         238
FT                   /note="R->A: Complete loss of RNA synthesis in vitro."
FT                   /evidence="ECO:0000269|PubMed:16476991"
FT   MUTAGEN         239
FT                   /note="R->A: Complete loss of RNA synthesis in vitro."
FT                   /evidence="ECO:0000269|PubMed:16476991"
FT   MUTAGEN         249
FT                   /note="R->A: Complete loss of RNA synthesis in vitro."
FT                   /evidence="ECO:0000269|PubMed:16476991"
FT   MUTAGEN         251
FT                   /note="F->A: 20% loss of RNA synthesis in vitro."
FT                   /evidence="ECO:0000269|PubMed:16476991"
FT   MUTAGEN         254
FT                   /note="F->A: 50% loss of RNA synthesis in vitro."
FT                   /evidence="ECO:0000269|PubMed:16476991"
FT   MUTAGEN         269
FT                   /note="S->A: 70% loss of RNA synthesis in vitro."
FT                   /evidence="ECO:0000269|PubMed:16476991"
FT   MUTAGEN         273
FT                   /note="V->A: 80% loss of RNA synthesis in vitro."
FT                   /evidence="ECO:0000269|PubMed:16476991"
FT   MUTAGEN         278
FT                   /note="K->A: Complete loss of RNA synthesis in vitro."
FT                   /evidence="ECO:0000269|PubMed:16476991"
FT   MUTAGEN         281
FT                   /note="K->A: Complete loss of RNA synthesis in vitro."
FT                   /evidence="ECO:0000269|PubMed:16476991"
SQ   SEQUENCE   757 AA;  86534 MW;  D5A0E8133CDE37F4 CRC64;
     MDVNPTLLFL KVPAQNAIST TFPYTGDPPY SHGTGTGYTM DTVNRTHQYS ERGRWTTNTE
     TGAPQLNPID GPLPEDNEPS GYAQTDCVLE AMAFLEESHP GIFETSCLET MEVVQQTRVD
     KLTQGRQTYD WTLNRNQPAA TALANTIEVF RSNGLTANES GRLIDFLKDV MESMNKEEME
     ITTHFQRKRR VRDNMTKKMV TQRTIGKRKQ RLNKRSYLIR ALTLNTMTKD AERGKLKRRA
     IATPGMQIRG FVYFVETLAR SICEKLEQSG LPVGGNEKKA KLANVVRKMM TNSQDTEISF
     TITGDNTKWN ENQNPRMFLA MITYITRNQP EWFRNVLSIA PIMFSNKMAR LGKGYMFESK
     SMKIRTQIPA EMLASIDLKY FNDSTRKKIE KIRPLLIDGT ASLSPGMMMG MFNMLSTVLG
     VSILNLGQKR HTKTTYWWDG LQSSDDFALI VNAPNHEGIQ AGVNRFYRTC KLLGINMSKK
     KSYINRTGTF EFTSFFYRYG FVANFSMELP SFGVSGINES ADMSIGVTVI KNNMINNDLG
     PATAQMALQL FIKDYRYTYR CHRGDTQIQT RRSFEIKKLW EQTHSKAGLL VSDGGPNLYN
     IRNLHIPEVC LKWELMDEDY QGRLCNPLNP FVNHKDIESV NNAVIMPAHG PAKNMEYDAV
     ATTHSWIPKR NRSILNTSQR GILEDEQMYQ KCCNLFEKFF PSSSYRRPVG ISSMVEAMVS
     RARIDARIDF ESGRIKKEEF TEIMKICSTI EELRRQK
//