Summary: RNA helicase
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RNA helicase Provide feedback
This family includes RNA helicases thought to be involved in duplex unwinding during viral RNA replication. Members of this family are found in a variety of single stranded RNA viruses.
Gorbalenya AE, Koonin EV, Donchenko AP, Blinov VM; , Nucleic Acids Res 1989;17:4713-4730.: Two related superfamilies of putative helicases involved in replication, recombination, repair and expression of DNA and RNA genomes. PUBMED:2546125 EPMC:2546125
Internal database links
|Similarity to PfamA using HHSearch:||AAA ABC_tran PPV_E1_C Parvo_NS1 Mg_chelatase Viral_helicase1 APS_kinase IstB_IS21 MMR_HSR1 Cytidylate_kin DUF258 Rad17 NTPase_1 RuvB_N DUF815 NACHT AAA_2 AAA_5 KTI12 AAA_14 AAA_16 AAA_17 AAA_18 AAA_22 AAA_23 AAA_24 AAA_28 AAA_29 AAA_33|
External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR000605
Helicases have been classified in 5 superfamilies (SF1-SF5). All of the proteins bind ATP and, consequently, all of them carry the classical Walker A (phosphate-binding loop or P-loop) and Walker B (Mg2+-binding aspartic acid) motifs. Superfamily 3 consists of helicases encoded mainly by small DNA viruses and some large nucleocytoplasmic DNA viruses [PUBMED:11689653, PUBMED:15037234]. Small viruses are very dependent on the host-cell machinery to replicate. SF3 helicase in small viruses is associated with an origin-binding domain. By pairing a domain that recognises the ori with a helicase, the virus can bypass the host-cell-based regulation pathway and initiate its own replication. The protein binds to the viral ori leading to origin unwinding. Cellular replication proteins are then recruited to the ori and the viral DNA is replicated.
In SF3 helicases the Walker A and Walker B motifs are separated by spacers of rather uniform, and relatively short, length. In addition to the A and B motifs this family is characterised by a third motif (C) which resides between the B motif and the C terminus of the conserved region. This motif consists of an Asn residue preceded by a run of hydrophobic residues [PUBMED:2156730].
Several structures of SF3 helicases have been solved [PUBMED:12774115]. They all possess the same core alpha/beta fold, consisting of a five-stranded parallel beta sheet flanked on both sides by several alpha helices. In contrast to SF1 and SF2 helicases, which have RecA-like core folds, the strand connectivity within the alpha/beta core domain is that of AAA+ proteins [PUBMED:15718137]. The SF3 helicase proteins assemble into a hexameric ring.
Some proteins known to contain an SF3 helicase domain are listed below:
- Polyomavirus large T antigen. It initiates DNA unwinding and replication via interactions with the viral origin of replication.
- Papillomavirus E1 protein. An ATP-dependent DNA helicase required for initiation of viral DNA replication.
- Parvovirus Rep/NS1 protein, which is also required for the initiation of viral replication.
- Poxviridae and other large DNA viruses D5 protein.
- Bacteriophage DNA primase/helicase protein.
- Bacterial prophage DNA primase/helicase protein.
The entry represents the core alpha/beta fold of the SF3 helicase domain found predominantly in DNA viruses.
|Molecular function||RNA binding (GO:0003723)|
|RNA helicase activity (GO:0003724)|
- the number of sequences which exhibit this architecture
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This example describes an architecture with one
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AAA family proteins often perform chaperone-like functions that assist in the assembly, operation, or disassembly of protein complexes .
The clan contains the following 198 members:6PF2K AAA AAA-ATPase_like AAA_10 AAA_11 AAA_12 AAA_13 AAA_14 AAA_15 AAA_16 AAA_17 AAA_18 AAA_19 AAA_2 AAA_21 AAA_22 AAA_23 AAA_24 AAA_25 AAA_26 AAA_27 AAA_28 AAA_29 AAA_3 AAA_30 AAA_31 AAA_32 AAA_33 AAA_34 AAA_35 AAA_5 AAA_6 AAA_7 AAA_8 AAA_PrkA ABC_ATPase ABC_tran Adeno_IVa2 Adenylsucc_synt ADK AFG1_ATPase AIG1 APS_kinase Arch_ATPase Arf ArgK ArsA_ATPase ATP-synt_ab ATP_bind_1 ATP_bind_2 Bac_DnaA CbiA CBP_BcsQ CDC73_C CLP1_P CMS1 CoaE CobA_CobO_BtuR CobU cobW CPT CTP_synth_N Cytidylate_kin Cytidylate_kin2 DAP3 DEAD DEAD_2 DLIC DNA_pack_C DNA_pack_N DNA_pol3_delta DNA_pol3_delta2 DnaB_C dNK DUF1611 DUF2075 DUF2478 DUF258 DUF2791 DUF2813 DUF3584 DUF463 DUF815 DUF853 DUF87 DUF927 Dynamin_N ERCC3_RAD25_C Exonuc_V_gamma FeoB_N Fer4_NifH Flavi_DEAD FTHFS FtsK_SpoIIIE G-alpha Gal-3-0_sulfotr GBP GTP_EFTU Gtr1_RagA Guanylate_kin GvpD HDA2-3 Helicase_C Helicase_C_2 Helicase_C_4 Helicase_RecD Herpes_Helicase Herpes_ori_bp Herpes_TK IIGP IPPT IPT IstB_IS21 KaiC KAP_NTPase KdpD Kinesin Kinesin-relat_1 Kinesin-related KTI12 Lon_2 LpxK MCM MEDS Mg_chelatase Microtub_bd MipZ MMR_HSR1 MobB MukB MutS_V Myosin_head NACHT NB-ARC NOG1 NTPase_1 NTPase_P4 ParA Parvo_NS1 PAXNEB PduV-EutP PhoH PIF1 Podovirus_Gp16 Polyoma_lg_T_C Pox_A32 PPK2 PPV_E1_C PRK Rad17 Rad51 Ras RecA ResIII RHD3 RHSP RNA12 RNA_helicase Roc RuvB_N SbcCD_C SecA_DEAD Septin Sigma54_activ_2 Sigma54_activat SKI SMC_N SNF2_N Spore_IV_A SRP54 SRPRB Sulfotransfer_1 Sulfotransfer_2 Sulfotransfer_3 Sulphotransf T2SSE T4SS-DNA_transf Terminase_1 Terminase_3 Terminase_6 Terminase_GpA Thymidylate_kin TIP49 TK TniB Torsin TraG-D_C tRNA_lig_kinase TrwB_AAD_bind TsaE UvrD-helicase UvrD_C UvrD_C_2 Viral_helicase1 VirC1 VirE Zeta_toxin Zot
We make a range of alignments for each Pfam-A family:
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Curation and family details
|Seed source:||Pfam-B_11 (release 3.0)|
|Number in seed:||99|
|Number in full:||6439|
|Average length of the domain:||97.00 aa|
|Average identity of full alignment:||35 %|
|Average coverage of the sequence by the domain:||6.86 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 80369284 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||18|
|Download:||download the raw HMM for this family|
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