Summary: Sigma-70 region 3
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Region 3 forms a discrete compact three helical domain within the sigma-factor. Region is not normally involved in the recognition of promoter DNA, but as some specific bacterial promoters containing an extended -10 promoter element, residues within region 3 play an important role. Region 3 primarily is involved in binding the core RNA polymerase in the holoenzyme .
Campbell EA, Muzzin O, Chlenov M, Sun JL, Olson CA, Weinman O, Trester-Zedlitz ML, Darst SA; , Mol Cell 2002;9:527-539.: Structure of the bacterial RNA polymerase promoter specificity sigma subunit. PUBMED:11931761 EPMC:11931761
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This tab holds annotation information from the InterPro database.
InterPro entry IPR007624
The bacterial core RNA polymerase complex, which consists of five subunits, is sufficient for transcription elongation and termination but is unable to initiate transcription. Transcription initiation from promoter elements requires a sixth, dissociable subunit called a sigma factor, which reversibly associates with the core RNA polymerase complex to form a holoenzyme [PUBMED:3052291]. RNA polymerase recruits alternative sigma factors as a means of switching on specific regulons. Most bacteria express a multiplicity of sigma factors. Two of these factors, sigma-70 (gene rpoD), generally known as the major or primary sigma factor, and sigma-54 (gene rpoN or ntrA) direct the transcription of a wide variety of genes. The other sigma factors, known as alternative sigma factors, are required for the transcription of specific subsets of genes.
With regard to sequence similarity, sigma factors can be grouped into two classes, the sigma-54 and sigma-70 families. Sequence alignments of the sigma70 family members reveal four conserved regions that can be further divided into subregions eg. sub-region 2.2, which may be involved in the binding of the sigma factor to the core RNA polymerase; and sub-region 4.2, which seems to harbor a DNA-binding 'helix-turn-helix' motif involved in binding the conserved -35 region of promoters recognised by the major sigma factors [PUBMED:3092189, PUBMED:1597408].Region 3 forms a discrete compact three helical domain within the sigma-factor. Region is not normally involved in the recognition of promoter DNA, but in some specific bacterial promoters containing an extended -10 promoter element, residues within region 3 play an important role. Region 3 primarily is involved in binding the core RNA polymerase in the holoenzyme [PUBMED:11931761].
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|Molecular function||DNA binding (GO:0003677)|
|sigma factor activity (GO:0016987)|
|sequence-specific DNA binding transcription factor activity (GO:0003700)|
|Biological process||regulation of transcription, DNA-templated (GO:0006355)|
|DNA-templated transcription, initiation (GO:0006352)|
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This family contains a diverse range of mostly DNA-binding domains that contain a helix-turn-helix motif.
The clan contains the following 217 members:AphA_like Arg_repressor ARID B-block_TFIIIC Bac_DnaA_C BetR Bot1p BrkDBD CENP-B_N Cro Crp CSN8_PSD8_EIF3K DDRGK Dimerisation Dimerisation2 DsrD DUF1133 DUF1153 DUF1323 DUF134 DUF1441 DUF1492 DUF1495 DUF1670 DUF1804 DUF1836 DUF1870 DUF2089 DUF2250 DUF2316 DUF2582 DUF3116 DUF3853 DUF387 DUF3908 DUF4364 DUF739 DUF742 DUF977 E2F_TDP Ets Exc F-112 FaeA Fe_dep_repr_C Fe_dep_repress FeoC Ftsk_gamma FUR GcrA GerE GntR HARE-HTH HemN_C Homeobox Homeobox_KN Homez HrcA_DNA-bdg HSF_DNA-bind HTH_1 HTH_10 HTH_11 HTH_12 HTH_13 HTH_15 HTH_16 HTH_17 HTH_18 HTH_19 HTH_20 HTH_21 HTH_22 HTH_23 HTH_24 HTH_25 HTH_26 HTH_27 HTH_28 HTH_29 HTH_3 HTH_30 HTH_31 HTH_32 HTH_33 HTH_34 HTH_35 HTH_36 HTH_37 HTH_38 HTH_39 HTH_40 HTH_41 HTH_42 HTH_43 HTH_45 HTH_46 HTH_47 HTH_5 HTH_6 HTH_7 HTH_8 HTH_9 HTH_AraC HTH_AsnC-type HTH_CodY HTH_Crp_2 HTH_DeoR HTH_IclR HTH_Mga HTH_micro HTH_OrfB_IS605 HTH_psq HTH_Tnp_1 HTH_Tnp_1_2 HTH_Tnp_4 HTH_Tnp_IS1 HTH_Tnp_IS630 HTH_Tnp_ISL3 HTH_Tnp_Mu_1 HTH_Tnp_Mu_2 HTH_Tnp_Tc3_1 HTH_Tnp_Tc3_2 HTH_Tnp_Tc5 HTH_WhiA HxlR IF2_N KORA KorB LacI LexA_DNA_bind LZ_Tnp_IS481 MADF_DNA_bdg MarR MarR_2 MerR MerR-DNA-bind MerR_1 MerR_2 Mga Mnd1 Mor MotA_activ MqsA_antitoxin MRP-L20 Myb_DNA-bind_2 Myb_DNA-bind_3 Myb_DNA-bind_4 Myb_DNA-bind_5 Myb_DNA-bind_6 Myb_DNA-bind_7 Myb_DNA-binding Neugrin NUMOD1 OST-HTH P22_Cro PaaX PadR PAX PCI Penicillinase_R Phage_AlpA Phage_antitermQ Phage_CI_repr Phage_CII Phage_rep_org_N Phage_terminase Pou Pox_D5 PuR_N Put_DNA-bind_N Rap1-DNA-bind Rep_3 RepA_C RepA_N RepC RepL Replic_Relax RFX_DNA_binding Ribosomal_S19e Ribosomal_S25 Rio2_N RNA_pol_Rpc34 RP-C RPA RPA_C RQC Rrf2 RTP RuvB_C SAC3_GANP SANT_DAMP1_like SatD SgrR_N Sigma54_CBD Sigma54_DBD Sigma70_ECF Sigma70_r2 Sigma70_r3 Sigma70_r4 Sigma70_r4_2 SLIDE SpoIIID Sulfolobus_pRN TBPIP Terminase_5 TetR_N TFIIE_alpha Tn916-Xis TraI_2_C Trans_reg_C TrfA TrmB Trp_repressor UPF0122 YdaS_antitoxin YokU z-alpha
We make a range of alignments for each Pfam-A family:
- the curated alignment from which the HMM for the family is built
- the alignment generated by searching the sequence database using the HMM
- Representative Proteomes (RPs) at 15%, 35%, 55% and 75% co-membership thresholds
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Curation and family details
|Number in seed:||71|
|Number in full:||43955|
|Average length of the domain:||76.90 aa|
|Average identity of full alignment:||33 %|
|Average coverage of the sequence by the domain:||20.61 %|
|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:||12|
|Download:||download the raw HMM for this family|
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There are 13 interactions for this family. More...
We determine these interactions using iPfam, which considers the interactions between residues in three-dimensional protein structures and maps those interactions back to Pfam families. You can find more information about the iPfam algorithm in the journal article that accompanies the website.
For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the Sigma70_r3 domain has been found. There are 74 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.
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