1SIG: RNA polymerase primary sigma factor

Crystal structure of a SIGMA70 subunit fragment from escherichia coli RNA polymerase. Determined by X-ray diffraction at 2.6 Å resolution. Released 15 May 1997.

Method: X-ray diffraction
Resolution: 2.6 Å
Organism: Escherichia coli
Chains: 1
Atoms: 2,593
Mol. weight: 39.09 kDa
Released: 15 May 1997

Explore 1SIG in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

1SIG contains 18 α-helices and 2 β-strands across 1 chain. 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: 18 helices, 2 β-strands

Element	Residues	Length	Sheet
α-helix	116-134	19
α-helix	138-148	11
α-helix	158-160	3
β-strand	162-165	4	1
α-helix	214-234	21
α-helix	243-256	14
β-strand	259-261	3	1
α-helix	263-288	26
α-helix	289-294	6
α-helix	299-306	8
α-helix	313-315	3
α-helix	317-320	4
α-helix	325-329	5
α-helix	330-332	3
α-helix	334-351	18
α-helix	355-382	28
α-helix	384-391	8
α-helix	401-418	18
α-helix	421-423	3
α-helix	427-445	19

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
RNA polymerase primary sigma factor	A	protein	339	Escherichia coli	P00579 (AlphaFold model)

Sequence of entity 1 (A), FASTA

>1SIG_1 RNA POLYMERASE PRIMARY SIGMA FACTOR (chains A)
GSHMEGEIDIAKRIEDGINQVQCSVAEYPEAITYLLEQYNRVEAEEARLSDLITGFVDPN
AEEDLAPTATHVGSELSQEDLDDDEDEDEEDGDDDSADDDNSIDPELAREKFAELRAQYV
VTRDTIKAKGRSHATAQEEILKLSEVFKQFRLVPKQFDYLVNSMRVMMDRVRTQERLIMK
LCVEQCKMPKKNFITLFTGNETSDTWFNAAIAMNKPWSEKLHDVSEEVHRALQKLQQIEE
ETGLTIEQVKDINRRMSIGEAKARRAKKEMVEANLRLVISIAKKYTNRGLQFLDLIQEGN
IGLMKAVDKFEYRRGYKFSTYATWWIRQAITRSIADQAR

Primary citation

Crystal structure of a sigma 70 subunit fragment from E. coli RNA polymerase. Malhotra, A., Severinova, E., Darst, S.A. Cell (1996) 87:127-136. DOI 10.1016/S0092-8674(00)81329-X · PubMed

Other PDB entries of the same protein (UniProt P00579 (AlphaFold model), which also has an AlphaFold model), best resolution first:

6XL5 2.5 Å, Cryo-EM structure of EcmrR-RNAP-promoter open complex (EcmrR-RPo)
6XL9 2.5 Å, Cryo-EM structure of EcmrR-RNAP-promoter initial transcribing complex with 3-nt RNA…
9YMV 2.6 Å, De novo initial transcribing RNA polymerase with pretranslocated 3-mer RNA / product…
6XLJ 2.7 Å, Cryo-EM structure of EcmrR-RNAP-promoter initial transcribing complex with 4-nt RNA…
6XLL 2.7 Å, Cryo-EM structure of E. coli RNAP-promoter initial transcribing complex with 5-nt RNA…
9YMU 2.7 Å, De novo initial transcribing RNA polymerase with 2-mer RNA and bound CTP / Michaelis…
9YMW 2.7 Å, De novo initial transcribing RNA polymerase with 5-mer RNA CCAUC (RPitc5a)
9YMX 2.7 Å, De novo initial transcribing RNA polymerase with 5-mer RNA AUCUA (RPitc5b)
8JO2 2.74 Å, Structural basis of transcriptional activation by the OmpR/PhoB-family response…
8FTD 2.76 Å, Structure of Escherichia coli CedA in complex with transcription initiation complex
8TO1 2.8 Å, Escherichia coli RNA polymerase unwinding intermediate (I1a) at the lambda PR promoter
7MKJ 2.9 Å, Cryo-EM structure of Escherichia coli RNA polymerase bound to T7A1 promoter DNA

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