2gsk

Structure of the BtuB:TonB Complex

Method: X-RAY DIFFRACTION

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1. Protein Identity and Related Structures Protein Identity & Related Structures

Vitamin B12 transporter btuB

Escherichia coli

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein heterocomplex	Heteromer	Protein 2	protein TONB × 1 （P94739） CALCIUM ION × 2 CYANOCOBALAMIN × 1 LAURYL DIMETHYLAMINE-N-OXIDE × 4 N-OCTANE × 3 HEXANE × 2 water × 2	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	BTUB_ECOLI
Isoform	—
PDB entities	1
Chains and sequence ranges	Author chain A； PDBConstruct 1–590； UniProt 25–614

protein TONB

Escherichia coli

UniProt P94739

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein heterocomplex	Heteromer	Protein 2	Vitamin B12 transporter btuB × 1 （P06129） CALCIUM ION × 2 CYANOCOBALAMIN × 1 LAURYL DIMETHYLAMINE-N-OXIDE × 4 N-OCTANE × 3 HEXANE × 2 water × 2	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	TONB_ECOLI
Isoform	—
PDB entities	2
Chains and sequence ranges	Author chain B； PDBConstruct 1–81； UniProt 153–233

The page prioritizes protein identity, the current assembly, associated components, oligomeric state and cross-PDB links. Chain mapping and sequence ranges are retained as data evidence. Internal IDs, import timestamps and assembly operation expressions are maintenance fields and are not shown here.

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2. Structure Basics 2. Structure Basics

Entry ID entry_id	2gsk
Deposition date deposition_date	2006-04-26
Structure title title	Structure of the BtuB:TonB Complex
Keywords keywords	OUTER-MEMBRANE ACTIVE TRANSPORT, BETA-BARREL, TONB, MEMBRANE PROTEIN, SIGNALING PROTEIN-MEMBRANE PROTEIN COMPLEX; SIGNALING PROTEIN/MEMBRANE PROTEIN
Experimental Method method	X-RAY DIFFRACTION

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3. Official assembly/model SAXS Official SAXS Profiles

This page reads only the latest assembly calculations. Every curve maps to an explicit PDB entry, official biological assembly and coordinate model.

2gsk__assembly_1__model_1

Assembly 1 · Model 1 · CRYSOL 4.1.3-1-20251215 (887e7ef)

Download this curve (.dat)

2gsk__assembly_1__model_1 | I(q)

100 plotted points; both axes use logarithmic scales.

2gsk__assembly_1__model_1 | P(r) · Pending

P(r) will be calculated and displayed separately for the same assembly/model.

Rg（Guinier）	25.76 Å
Rg (electron density)	25.11 Å
Total Rg	25.95 Å
Atom count	5384
Residues	671
Excluded volume	95211 Å³
Maximum q	0.500 Å⁻¹

Assembly	Model	Structure unit	Oligomeric description	Status	CRYSOL	Actions
1	1	`2gsk__assembly_1__model_1`	dimeric （2）	Success	4.1.3-1-20251215 (887e7ef)	View Download

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4. Crystallography and Experiment 4. Crystallography & Experiment

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5. Entities and Polymers Entities & Polymers (8)

Entity 1 Entity 1 polymer

Description description	Vitamin B12 transporter btuB
Molecular weight formula_weight	65954.8 kDa
Source method src_method	man
Copy count entity_count	1

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	A
Atom count atom_count	5658

PDTLVVTANRFEQPRSTVLAPTTVVTRQDIDRWQSTSVNDVLRRLPGVDITQNGGSGQLSSIFIRGTNASHVLVLIDGVRLNLAGVSGSADLSQFPIALVQRVEYIRGPRSAVYGSDAIGGVVNIITTRDEPGTEISAGWGSNSYQNYDVSTQQQLGDKTRVTLLGDYAHTHGYDVVAYGNTGTQAQTDNDGFLSKTLYGALEHNFTDAWSGFVRGYGYDNRTNYDAYYSPGSPLLDTRKLYSQSWDAGLRYNGELIKSQLITSYSHSKDYNYDPHYGRYDSSATLDEMKQYTVQWANNVIVGHGSIGAGVDWQKQTTTPGTGYVEDGYDQRNTGIYLTGLQQVGDFTFEGAARSDDNSQFGRHGTWQTSAGWEFIEGYRFIASYGTSYKAPNLGQLYGFYGNPNLDPEKSKQWEGAFEGLTAGVNWRISGYRNDVSDLIDYDDHTLKYYNEGKARIKGVEATANFDTGPLTHTVSYDYVDARNAITDTPLLRRAKQQVKYQLDWQLYDFDWGITYQYLGTRYDKDYSSYPYQTVKMGGVSLWDLAVAYPVTSHLTVRGKIANLFDKDYETVYGYQTAGREYTLSGSYTF

Source Source

Source organism organism	Escherichia coli
NCBI taxonomy ID ncbi_taxonomy_id	562
Host organism host_organism	Escherichia coli

Entity 2 Entity 2 polymer

Description description	protein TONB
Molecular weight formula_weight	9247.7 kDa
Source method src_method	man
Copy count entity_count	1

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	B

PRALSRNQPQYPARAQALRIEGQVKVKFDVTPDGRVDNVQILSAKPANMFEREVKNAMRRWRYEPGKPGSGIVVNILFKIN

Source Source

Source organism organism	Escherichia coli
NCBI taxonomy ID ncbi_taxonomy_id	562
Host organism host_organism	Escherichia coli BL21(DE3)

Entity 3 Entity 3 non-polymer

Description description	CALCIUM ION
Molecular weight formula_weight	40.1 kDa
Source method src_method	syn
Copy count entity_count	2

Entity 4 Entity 4 non-polymer

Description description	CYANOCOBALAMIN
Molecular weight formula_weight	1356.4 kDa
Source method src_method	syn
Copy count entity_count	1

Entity 5 Entity 5 non-polymer

Description description	LAURYL DIMETHYLAMINE-N-OXIDE
Molecular weight formula_weight	229.4 kDa
Source method src_method	syn
Copy count entity_count	4

Entity 6 Entity 6 non-polymer

Description description	N-OCTANE
Molecular weight formula_weight	114.2 kDa
Source method src_method	syn
Copy count entity_count	3

Entity 7 Entity 7 non-polymer

Description description	HEXANE
Molecular weight formula_weight	86.2 kDa
Source method src_method	syn
Copy count entity_count	2

Entity 8 Entity 8 water

Description description	water
Molecular weight formula_weight	18.0 kDa
Source method src_method	nat
Copy count entity_count	274

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6. Fold Classification (SCOP + CATH) 5 domains

SCOP 2.08 (2 domains)

Domain ID domain_id	d2gska_
Class class	f — Membrane and cell surface proteins and peptides
Fold Fold fold	f.4 — Transmembrane beta-barrels
Superfamily Superfamily superfamily	f.4.3 — Porins
Family Family family	f.4.3.3 — Ligand-gated protein channel

Domain ID domain_id	d2gskb_
Class class	d — Alpha and beta proteins (a+b)
Fold Fold fold	d.212 — TolA/TonB C-terminal domain
Superfamily Superfamily superfamily	d.212.1 — TolA/TonB C-terminal domain
Family Family family	d.212.1.2 — TonB

CATH v4.4 (3 domains)

Domain ID domain_id	2gskA01
Class class	2 — Mainly Beta
Architecture architecture	170 — Beta Complex
Topology topology	130 — Ferric Hydroxamate Uptake Protein; Chain A, domain 1
Homologous superfamily homologous superfamily	10 — TonB-dependent receptor, plug domain

Domain ID domain_id	2gskA02
Class class	2 — Mainly Beta
Architecture architecture	40 — Beta Barrel
Topology topology	170 — Maltoporin; Chain A
Homologous superfamily homologous superfamily	20 — TonB-dependent receptor, beta-barrel domain

Domain ID domain_id	2gskB00
Class class	3 — Alpha Beta
Architecture architecture	30 — 2-Layer Sandwich
Topology topology	2420 — TolA/TonB C-terminal domain
Homologous superfamily homologous superfamily	10 — TonB

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Unit-cell length a length_a	74.340 Å
Unit-cell length b length_b	82.439 Å
Unit-cell length c length_c	122.632 Å
Unit-cell angle α angle_alpha	90.00 °
Unit-cell angle β angle_beta	90.00 °
Unit-cell angle γ angle_gamma	90.00 °
Molecules per unit cell Z z_pdb	4

Space group space_group	P 21 21 21
Space-group number int_tables_number	19
Crystal system crystal_system	—

Resolution resolution	2.100 Å
Low-resolution limit resolution_low	40.000 Å
R factor r_factor	0.1970
R_work r_work	0.1960
R_free r_free	0.2510

Structure of the BtuB:TonB Complex

1. Protein Identity and Related Structures Protein Identity & Related Structures

Vitamin B12 transporter btuB

State in the Current Structure

Other States of the Same Protein in the Database

protein TONB

State in the Current Structure

Other States of the Same Protein in the Database

2. Structure Basics 2. Structure Basics

3. Official assembly/model SAXS Official SAXS Profiles

2gsk__assembly_1__model_1

2gsk__assembly_1__model_1 | I(q)

2gsk__assembly_1__model_1 | P(r) · Pending

4. Crystallography and Experiment 4. Crystallography & Experiment

Unit cell Unit Cell

Symmetry Symmetry

Refinement Refinement

Diffraction experiment Diffraction

5. Entities and Polymers Entities & Polymers (8)

Entity 1 Entity 1 polymer

Polymer Polymer

Source Source

Entity 2 Entity 2 polymer

Polymer Polymer

Source Source

Entity 3 Entity 3 non-polymer

Entity 4 Entity 4 non-polymer

Entity 5 Entity 5 non-polymer

Entity 6 Entity 6 non-polymer

Entity 7 Entity 7 non-polymer

Entity 8 Entity 8 water

6. Fold Classification (SCOP + CATH) 5 domains

SCOP 2.08 (2 domains)

CATH v4.4 (3 domains)

7. Citations (2)

Structure of the BtuB:TonB Complex

1. Protein Identity and Related Structures Protein Identity & Related Structures

Vitamin B12 transporter btuB

State in the Current Structure

Other States of the Same Protein in the Database

Monomer

Homodimer

Homotetramer

Other homooligomers

Heteromeric or nucleic-acid complex

protein TONB

State in the Current Structure

Other States of the Same Protein in the Database

Monomer

Homodimer

Homotetramer

Other homooligomers

Heteromeric or nucleic-acid complex

2. Structure Basics 2. Structure Basics

3. Official assembly/model SAXS Official SAXS Profiles

2gsk__assembly_1__model_1

2gsk__assembly_1__model_1 | I(q)

2gsk__assembly_1__model_1 | P(r) · Pending

4. Crystallography and Experiment 4. Crystallography & Experiment

Unit cell Unit Cell

Symmetry Symmetry

Refinement Refinement

Diffraction experiment Diffraction

5. Entities and Polymers Entities & Polymers (8)

Entity 1 Entity 1 polymer

Polymer Polymer

Source Source

Entity 2 Entity 2 polymer

Polymer Polymer

Source Source

Entity 3 Entity 3 non-polymer

Entity 4 Entity 4 non-polymer

Entity 5 Entity 5 non-polymer

Entity 6 Entity 6 non-polymer

Entity 7 Entity 7 non-polymer

Entity 8 Entity 8 water

6. Fold Classification (SCOP + CATH) 5 domains

SCOP 2.08 (2 domains)

CATH v4.4 (3 domains)

7. Citations (2)