9KCH: Tol-Pal system protein TolQ

Cryo-EM structure of inner membrane TolQRA complex in CYMAL-6-Neopentyl Glycol detergent micelles. Determined by electron microscopy at 4.19 Å resolution. Released 9 Jul 2025.

Method: Electron microscopy
Resolution: 4.19 Å
Organism: Escherichia coli K-12
Chains: 8
Atoms: 9,121
Mol. weight: 204.84 kDa
Released: 9 Jul 2025

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

Secondary structure: helices and β-sheets

9KCH contains 44 α-helices and 0 β-strands across 8 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: 11 helices, 0 β-strands

Element	Residues	Length
α-helix	17-56	40
α-helix	62-68	7
α-helix	73-75	3
α-helix	79-96	18
α-helix	104-123	20
α-helix	127-134	8
α-helix	137-155	19
α-helix	160-162	3
α-helix	165-167	3
α-helix	168-181	14
α-helix	185-221	37

Chain B: 6 helices, 0 β-strands

Element	Residues	Length
α-helix	15-55	41
α-helix	62-71	10
α-helix	80-95	16
α-helix	101-123	23
α-helix	127-158	32
α-helix	168-219	52

Chain C: 6 helices, 0 β-strands

Element	Residues	Length
α-helix	15-56	42
α-helix	62-70	9
α-helix	79-94	16
α-helix	104-123	20
α-helix	127-158	32
α-helix	168-223	56

Chain D: 8 helices, 0 β-strands

Element	Residues	Length
α-helix	15-56	42
α-helix	62-69	8
α-helix	70-72	3
α-helix	78-95	18
α-helix	101-123	23
α-helix	127-156	30
α-helix	168-183	16
α-helix	185-221	37

Chain E: 10 helices, 0 β-strands

Element	Residues	Length
α-helix	22-56	35
α-helix	62-70	9
α-helix	73-75	3
α-helix	79-95	17
α-helix	101-103	3
α-helix	104-124	21
α-helix	127-143	17
α-helix	145-154	10
α-helix	168-183	16
α-helix	185-221	37

Chain F: 1 helix, 0 β-strands

Element	Residues	Length	Sheet
α-helix	21-30	10

Chain G: 1 helix, 0 β-strands

Element	Residues	Length	Sheet
α-helix	19-33	15

Chain H: 1 helix, 0 β-strands

Element	Residues	Length	Sheet
α-helix	9-32	24

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Tol-Pal system protein TolQ	A, B, C, D, E	protein	230	Escherichia coli K-12	P0ABU9 (AlphaFold model)
Tol-Pal system protein TolR	F, G	protein	152	Escherichia coli K-12	P0ABV6 (AlphaFold model)
Tol-Pal system protein TolA	H	protein	421	Escherichia coli K-12	P19934 (AlphaFold model)

Sequence of entity 1 (A, B, C, D, E), FASTA

>9KCH_1 Tol-Pal system protein TolQ (chains A, B, C, D, E)
MTDMNILDLFLKASLLVKLIMLILIGFSIASWAIIIQRTRILNAAAREAEAFEDKFWSGI
ELSRLYQESQGKRDNLTGSEQIFYSGFKEFVRLHRANSHAPEAVVEGASRAMRISMNREL
ENLETHIPFLGTVGSISPYIGLFGTVWGIMHAFIALGAVKQATLQMVAPGIAEALIATAI
GLFAAIPAVMAYNRLNQRVNKLELNYDNFMEEFTAILHRQAFTVSESNKG

Sequence of entity 2 (F, G), FASTA

>9KCH_2 Tol-Pal system protein TolR (chains F, G)
MARARGRGRRDLKSEINIVPLLDVLLVLLLIFMATAPIITQSVEVDLPDATESQAVSSND
NPPVIVEVSGIGQYTVVVEKDRLERLPPEQVVAEVSSRFKANPKTVFLIGGAKDVPYDEI
IKALNLLHSAGVKSVGLMTQPILEHHHHHHHH

Sequence of entity 3 (H), FASTA

>9KCH_3 Tol-Pal system protein TolA (chains H)
MSKATEQNDKLKRAIIISAVLHVILFAALIWSSFDENIEASAGGGGGSSIDAVMVDSGAV
VEQYKRMQSQESSAKRSDEQRKMKEQQAAEELREKQAAEQERLKQLEKERLAAQEQKKQA
EEAAKQAELKQKQAEEAAAKAAADAKAKAEADAKAAEEAAKKAAADAKKKAEAEAAKAAA
EAQKKAEAAAAALKKKAEAAEAAAAEARKKAATEAAEKAKAEAEKKAAAEKAAADKKAAA
EKAAADKKAAEKAAAEKAAADKKAAAEKAAADKKAAAAKAAAEKAAAAKAAAEADDIFGE
LSSGKNAPKTGGGAKGNNASPAGSGNTKNNGASGADINNYAGQIKSAIESKFYDASSYAG
KTCTLRIKLAPDGMLLDIKPEGGDPALCQAALAAAKLAKIPKPPSQAVYEVFKNAPLDFK
P

Primary citation

Structural Insights into the Force-Transducing Mechanism of a Motor-Stator Complex Important for Bacterial Outer Membrane Lipid Homeostasis. Yeow, J., Chia, C.G., Lim, N.Z. et al. J Am Chem Soc (2025) 147:24299-24308. DOI 10.1021/jacs.4c18050 · PubMed

Other PDB entries of the same protein (UniProt P0ABU9 (AlphaFold model), which also has an AlphaFold model), best resolution first:

9O40 2.92 Å, cryo-EM structure of TolQR conformation1 in SMA nanodiscs
9DDM 2.94 Å, E. coli TolAQR conformation I
9DDN 3.18 Å, E. coli TolAQR conformation II
9KPZ 3.18 Å, Structure of TolQRA complex at pH 5.4 from E.coli
9QUQ 3.28 Å, cryo-EM structure of TolQR conformation2 in SMA nanodiscs
9QVD 3.52 Å, cryo-EM structure of TolQRA in nanodiscs
9K49 3.6 Å, Cryo-EM structure of inner membrane TolQRA complex in CYMAL-6-Neopentyl Glycol detergent…
9KQ0 3.6 Å, Structure of TolQRA complex at pH 8.0 from E.coli
8ODT 4.2 Å, Structure of TolQR complex from E.coli

Browse structure collections

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