9MSF: Transcriptional regulator

de novo SigN RNA polymerase transcription initiation intermediate with post-catalytic bEBP state (RPi1 closed ring). Determined by electron microscopy at 2.6 Å resolution. Released 13 Aug 2025.

Method
Electron microscopy
Resolution
2.6 Å
Organisms
Aquifex aeolicus VF5, Escherichia coli
Chains
16
Atoms
44,073
Mol. weight
743.3 kDa
Ligands
ATP, ZN, POP, ADP
Released
13 Aug 2025

Explore 9MSF in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

9MSF contains 274 α-helices and 300 β-strands across 12 chains. Residue ranges use author residue numbering, as in the PDB file, from PDBe. To see them in 3D, choose the Cartoon representation with Secondary structure coloring: helices, sheets and coils get different colors.

Chain A: 16 helices, 11 β-strands

ElementResiduesLengthSheet
α-helix144-15613
β-strand163-16751
α-helix173-18210
β-strand191-19551
α-helix201-2033
α-helix204-2096
β-strand210-21122
β-strand223-22422
α-helix226-2294
β-strand234-23851
α-helix240-2423
α-helix245-25713
β-strand259-26023
β-strand269-27023
β-strand274-27961
α-helix283-2897
α-helix294-3007
β-strand304-30741
α-helix308-3092
α-helix310-3123
α-helix314-3163
α-helix317-33216
β-strand338-33924
α-helix341-3499
α-helix355-36814
β-strand374-37524
α-helix377-3837
Chain B: 15 helices, 12 β-strands
ElementResiduesLengthSheet
α-helix144-15512
β-strand163-16645
α-helix173-18311
β-strand191-19555
α-helix196-1983
α-helix201-2033
α-helix204-2096
β-strand210-21126
β-strand223-22426
α-helix226-2294
β-strand234-23855
α-helix240-2423
α-helix245-2484
α-helix249-2513
β-strand259-26027
β-strand26316
β-strand269-27027
β-strand274-27965
α-helix283-2886
α-helix294-3007
β-strand303-30645
α-helix317-33115
β-strand33918
α-helix341-3499
α-helix355-36814
β-strand37518
α-helix378-3814
Chain C: 15 helices, 12 β-strands
ElementResiduesLengthSheet
α-helix144-15512
β-strand163-16759
α-helix173-18210
β-strand191-19559
α-helix204-2085
β-strand211110
β-strand223110
α-helix226-2294
β-strand234-23859
α-helix240-2423
α-helix245-2484
α-helix249-2513
α-helix252-2565
β-strand259-260211
β-strand263110
β-strand269-270211
β-strand274-27969
α-helix283-2897
α-helix294-3007
β-strand303-30759
α-helix314-3163
α-helix317-33115
β-strand338-339212
α-helix341-3499
α-helix355-36814
β-strand374-375212
α-helix377-3837
Chain D: 17 helices, 12 β-strands
ElementResiduesLengthSheet
α-helix144-15512
β-strand163-166413
α-helix173-18311
β-strand191-195513
α-helix196-1983
α-helix201-2033
α-helix204-2096
β-strand210-211214
β-strand223-224214
α-helix226-2294
β-strand234-238513
α-helix240-2423
α-helix245-2484
α-helix249-2513
α-helix253-2575
β-strand259-261315
β-strand263114
β-strand268-270315
β-strand274-279613
α-helix283-2897
α-helix294-3007
β-strand303-306413
α-helix307-3093
α-helix310-3123
α-helix317-33216
β-strand339116
α-helix341-3477
α-helix355-36814
β-strand375116
Chain E: 13 helices, 12 β-strands
ElementResiduesLengthSheet
α-helix144-15613
β-strand163-166417
α-helix173-18311
β-strand191-195517
α-helix201-2033
α-helix204-2096
β-strand211118
β-strand223118
α-helix226-2294
β-strand234-238517
α-helix247-2493
α-helix252-2576
β-strand259-260219
β-strand263118
β-strand269-270219
β-strand274-279617
α-helix283-2886
α-helix294-3007
β-strand303-306417
α-helix310-3123
α-helix318-33215
β-strand338-339220
α-helix341-3499
α-helix355-36814
β-strand374-375220
Chain F: 14 helices, 12 β-strands
ElementResiduesLengthSheet
α-helix144-15613
β-strand163-167521
α-helix173-18311
β-strand191-195521
α-helix201-2033
α-helix204-2085
β-strand210-211222
β-strand223-224222
α-helix226-2294
β-strand234-238521
α-helix240-2423
α-helix245-25713
β-strand259-261323
β-strand263122
β-strand268-270323
β-strand274-279621
α-helix283-2886
α-helix294-3007
β-strand303-307521
α-helix310-3123
α-helix317-33216
β-strand338-339224
α-helix341-3499
α-helix355-36915
β-strand374-375224
α-helix377-3837
Chain G: 13 helices, 18 β-strands
ElementResiduesLengthSheet
α-helix8-114
β-strand12-18725
β-strand23-31925
α-helix35-5016
β-strand52-611026
β-strand74127
α-helix78-858
β-strand90-92328
β-strand97-105926
β-strand108-111427
α-helix112-1143
β-strand115126
α-helix116-1172
β-strand121-123328
β-strand129-133527
β-strand139-1501226
β-strand152-153229
α-helix166-1672
β-strand170-172326
β-strand175-176229
β-strand180-1891025
β-strand199-207925
α-helix213-23220
α-helix251-2544
β-strand256130
α-helix257-2593
α-helix264-2729
β-strand277130
α-helix278-2825
α-helix286-2916
α-helix297-30812
Chain H: 6 helices, 15 β-strands
ElementResiduesLengthSheet
β-strand13-20831
β-strand23-31931
α-helix35-4915
β-strand52-611032
β-strand74133
α-helix78-869
β-strand90-92334
β-strand97-105932
β-strand108-111433
α-helix112-1143
α-helix116-1172
β-strand121-123334
β-strand129-133533
β-strand139-1501232
β-strand152-153235
α-helix155-1584
β-strand170-172332
β-strand175-176235
β-strand180-1901131
β-strand198-2071031
α-helix213-22614

4 more chain groups are not listed. Open the entry in the viewer and use the sequence panel to see them.

Molecules and chains

MoleculeChainsTypeLengthOrganismUniProt
Transcriptional regulator (NtrC family)A, B, C, D, E, Fprotein268Aquifex aeolicus VF5O67198 (AlphaFold model)
DNA-directed RNA polymerase subunit alphaG, Hprotein329Escherichia coliP0A7Z4 (AlphaFold model)
DNA-directed RNA polymerase subunit betaIprotein1342Escherichia coliP0A8V2 (AlphaFold model)
DNA-directed RNA polymerase subunit beta'Jprotein1415Escherichia coliP0A8T7 (AlphaFold model)
DNA-directed RNA polymerase subunit omegaKprotein91Escherichia coliP0A800
RNA polymerase sigma-54 factorMprotein477Escherichia coliP24255
dhsU (-60 to +30) non-template strandS, UDNA90Aquifex aeolicus VF5
dhsU (-60 to +30) template strandT, VDNA90Aquifex aeolicus VF5
Sequence of entity 1 (A, B, C, D, E, F), FASTA
>9MSF_1 Transcriptional regulator (NtrC family) (chains A, B, C, D, E, F)
MLRKENELLRREKDLKEEEYVFESPKMKEILEKIKKISCAECPVLITGESGVGKEVVARL
IHKLSDRSKEPFVALNVASIPRDIFEAELFGYEKGAFTGAVSSKEGFFELADGGTLFLDE
IGELSLEAQAKLLRVIESGKFYRLGGRKEIEVNVRILAATNRNIKELVKEGKFREDLYYR
LGVIEIEIPPLRERKEDIIPLANHFLKKFSRKYAKEVEGFTKSAQELLLSYPWYGNVREL
KNVIERAVLFSEGKFIDRGELSCLVNSK
Sequence of entity 2 (G, H), FASTA
>9MSF_2 DNA-directed RNA polymerase subunit alpha (chains G, H)
MQGSVTEFLKPRLVDIEQVSSTHAKVTLEPLERGFGHTLGNALRRILLSSMPGCAVTEVE
IDGVLHEYSTKEGVQEDILEILLNLKGLAVRVQGKDEVILTLNKSGIGPVTAADITHDGD
VEIVKPQHVICHLTDENASISMRIKVQRGRGYVPASTRIHSEEDERPIGRLLVDACYSPV
ERIAYNVEAARVEQRTDLDKLVIEMETNGTIDPEEAIRRAATILAEQLEAFVDLRDVRQP
EVKEEKPEFDPILLRPVDDLELTVRSANCLKAEAIHYIGDLVQRTEVELLKTPNLGKKSL
TEIKDVLASRGLSLGMRLENWPPASIADE
Sequence of entity 3 (I), FASTA
>9MSF_3 DNA-directed RNA polymerase subunit beta (chains I)
MVYSYTEKKRIRKDFGKRPQVLDVPYLLSIQLDSFQKFIEQDPEGQYGLEAAFRSVFPIQ
SYSGNSELQYVSYRLGEPVFDVQECQIRGVTYSAPLRVKLRLVIYEREAPEGTVKDIKEQ
EVYMGEIPLMTDNGTFVINGTERVIVSQLHRSPGVFFDSDKGKTHSSGKVLYNARIIPYR
GSWLDFEFDPKDNLFVRIDRRRKLPATIILRALNYTTEQILDLFFEKVIFEIRDNKLQME
LVPERLRGETASFDIEANGKVYVEKGRRITARHIRQLEKDDVKLIEVPVEYIAGKVVAKD
YIDESTGELICAANMELSLDLLAKLSQSGHKRIETLFTNDLDHGPYISETLRVDPTNDRL
SALVEIYRMMRPGEPPTREAAESLFENLFFSEDRYDLSAVGRMKFNRSLLREEIEGSGIL
SKDDIIDVMKKLIDIRNGKGEVDDIDHLGNRRIRSVGEMAENQFRVGLVRVERAVKERLS
LGDLDTLMPQDMINAKPISAAVKEFFGSSQLSQFMDQNNPLSEITHKRRISALGPGGLTR
ERAGFEVRDVHPTHYGRVCPIETPEGPNIGLINSLSVYAQTNEYGFLETPYRKVTDGVVT
DEIHYLSAIEEGNYVIAQANSNLDEEGHFVEDLVTCRSKGESSLFSRDQVDYMDVSTQQV
VSVGASLIPFLEHDDANRALMGANMQRQAVPTLRADKPLVGTGMERAVAVDSGVTAVAKR
GGVVQYVDASRIVIKVNEDEMYPGEAGIDIYNLTKYTRSNQNTCINQMPCVSLGEPVERG
DVLADGPSTDLGELALGQNMRVAFMPWNGYNFEDSILVSERVVQEDRFTTIHIQELACVS
RDTKLGPEEITADIPNVGEAALSKLDESGIVYIGAEVTGGDILVGKVTPKGETQLTPEEK
LLRAIFGEKASDVKDSSLRVPNGVSGTVIDVQVFTRDGVEKDKRALEIEEMQLKQAKKDL
SEELQILEAGLFSRIRAVLVAGGVEAEKLDKLPRDRWLELGLTDEEKQNQLEQLAEQYDE
LKHEFEKKLEAKRRKITQGDDLAPGVLKIVKVYLAVKRRIQPGDKMAGRHGNKGVISKIN
PIEDMPYDENGTPVDIVLNPLGVPSRMNIGQILETHLGMAAKGIGDKINAMLKQQQEVAK
LREFIQRAYDLGADVRQKVDLSTFSDEEVMRLAENLRKGMPIATPVFDGAKEAEIKELLK
LGDLPTSGQIRLYDGRTGEQFERPVTVGYMYMLKLNHLVDDKMHARSTGSYSLVTQQPLG
GKAQFGGQRFGEMEVWALEAYGAAYTLQEMLTVKSDDVNGRTKMYKNIVDGNHQMEPGMP
ESFNVLLKEIRSLGINIELEDE
Sequence of entity 4 (J), FASTA
>9MSF_4 DNA-directed RNA polymerase subunit beta' (chains J)
MKDLLKFLKAQTKTEEFDAIKIALASPDMIRSWSFGEVKKPETINYRTFKPERDGLFCAR
IFGPVKDYECLCGKYKRLKHRGVICEKCGVEVTQTKVRRERMGHIELASPTAHIWFLKSL
PSRIGLLLDMPLRDIERVLYFESYVVIEGGMTNLERQQILTEEQYLDALEEFGDEFDAKM
GAEAIQALLKSMDLEQECEQLREELNETNSETKRKKLTKRIKLLEAFVQSGNKPEWMILT
VLPVLPPDLRPLVPLDGGRFATSDLNDLYRRVINRNNRLKRLLDLAAPDIIVRNEKRMLQ
EAVDALLDNGRRGRAITGSNKRPLKSLADMIKGKQGRFRQNLLGKRVDYSGRSVITVGPY
LRLHQCGLPKKMALELFKPFIYGKLELRGLATTIKAAKKMVEREEAVVWDILDEVIREHP
VLLNRAPTLHRLGIQAFEPVLIEGKAIQLHPLVCAAYNADFDGDQMAVHVPLTLEAQLEA
RALMMSTNNILSPANGEPIIVPSQDVVLGLYYMTRDCVNAKGEGMVLTGPKEAERLYRSG
LASLHARVKVRITEYEKDANGELVAKTSLKDTTVGRAILWMIVPKGLPYSIVNQALGKKA
ISKMLNTCYRILGLKPTVIFADQIMYTGFAYAARSGASVGIDDMVIPEKKHEIISEAEAE
VAEIQEQFQSGLVTAGERYNKVIDIWAAANDRVSKAMMDNLQTETVINRDGQEEKQVSFN
SIYMMADSGARGSAAQIRQLAGMRGLMAKPDGSIIETPITANFREGLNVLQYFISTHGAR
KGLADTALKTANSGYLTRRLVDVAQDLVVTEDDCGTHEGIMMTPVIEGGDVKEPLRDRVL
GRVTAEDVLKPGTADILVPRNTLLHEQWCDLLEENSVDAVKVRSVVSCDTDFGVCAHCYG
RDLARGHIINKGEAIGVIAAQSIGEPGTQLTMRTFHIGGAASRAAAESSIQVKNKGSIKL
SNVKSVVNSSGKLVITSRNTELKLIDEFGRTKESYKVPYGAVLAKGDGEQVAGGETVANW
DPHTMPVITEVSGFVRFTDMIDGQTITRQTDELTGLSSLVVLDSAERTAGGKDLRPALKI
VDAQGNDVLIPGTDMPAQYFLPGKAIVQLEDGVQISSGDTLARIPQESGGTKDITGGLPR
VADLFEARRPKEPAILAEISGIVSFGKETKGKRRLVITPVDGSDPYEEMIPKWRQLNVFE
GERVERGDVISDGPEAPHDILRLRGVHAVTRYIVNEVQDVYRLQGVKINDKHIEVIVRQM
LRKATIVNAGSSDFLEGEQVEYSRVKIANRELEANGKVGATYSRDLLGITKASLATESFI
SAASFQETTRVLTEAAVAGKRDELRGLKENVIVGRLIPAGTGYAYHQDRMRRRAAGEAPA
APQVTAEDASASLAELLNAGLGGSDNELELEVLFQ
Sequence of entity 5 (K), FASTA
>9MSF_5 DNA-directed RNA polymerase subunit omega (chains K)
MARVTVQDAVEKIGNRFDLVLVAARRARQMQVGGKDPLVPEENDKTTVIALREIEEGLIN
NQILDVRERQEQQEQEAAELQAVTAIAEGRR
Sequence of entity 6 (M), FASTA
>9MSF_6 RNA polymerase sigma-54 factor (chains M)
MKQGLQLRLSQQLAMTPQLQQAIRLLQLSTLELQQELQQALESNPLLEQIDTHEEIDTRE
TQDSETLDTADALEQKEMPEELPLDASWDTIYTAGTPSGTSGDYIDDELPVYQGETTQTL
QDYLMWQVELTPFSDTDRAIATSIVDAVDETGYLTVPLEDILESIGDEEIDIDEVEAVLK
RIQRFDPVGVAAKDLRDCLLIQLSQFDKTTPWLEEARLIISDHLDLLANHDFRTLMRVTR
LKEDVLKEAVNLIQSLDPRPGQSIQTGEPEYVIPDVLVRKHNGHWTVELNSDSIPRLQIN
QHYASMCNNARNDGDSQFIRSNLQDAKWLIKSLESRNDTLLRVSRCIVEQQQAFFEQGEE
YMKPMVLADIAQAVEMHESTISRVTTQKYLHSPRGIFELKYFFSSHVNTEGGGEASSTAI
RALVKKLIAAENPAKPLSDSKLTSLLSEQGIMVARRTVAKYRESLSIPPSNQRKQLV
Sequence of entity 7 (S, U), FASTA
>9MSF_7 dhsU (-60 to +30) non-template strand (chains S, U)
CGCAAGTTCCTTAGAATTTCAGTGTCCAGAAATTGGCACGAAAATTGCAATAAATACAAC
GAACAAAAATGGAGGTAAGAGTATGGGTGG
Sequence of entity 8 (T, V), FASTA
>9MSF_8 dhsU (-60 to +30) template strand (chains T, V)
CCACCCATACTCTTACCTCCATTTTTGTTCGTTGTATTTATTGCAATTTTCGTGCCAATT
TCTGGACACTGAAATTCTAAGGAACTTGCG

Ligands and cofactors

IDNameFormulaCopies
ATPAdenosine-5'-triphosphateC10 H16 N5 O13 P35
ZNZinc ionZn2
POPPyrophosphate 2-H2 O7 P21
ADPAdenosine-5'-diphosphateC10 H15 N5 O10 P21
MGMagnesium ionMg2

Primary citation

Real-time capture of sigma N transcription initiation intermediates reveals mechanism of ATPase-driven activation by limited unfolding. Mueller, A.U., Molina, N., Nixon, B.T. et al. Nat Commun (2025) 16:7138-7138. DOI 10.1038/s41467-025-61837-4 · PubMed

Other PDB entries of the same protein (UniProt O67198 (AlphaFold model), which also has an AlphaFold model), best resolution first:

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