2r6g

The Crystal Structure of the E. coli Maltose Transporter

Method: X-RAY DIFFRACTION

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

Maltose/maltodextrin import ATP-binding protein malK

Escherichia coli

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Other combination	Heteromer	Protein 5 其他Polymer 1	Maltose-binding periplasmic protein × 1 （P0AEX9） Maltose transport system permease protein malF × 1 （P02916） Maltose transport system permease protein malG × 1 （P68183） alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose × 1 ADENOSINE-5'-TRIPHOSPHATE × 2	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	MALK_ECOUT
Isoform	—
PDB entities	1
Chains and sequence ranges	Author chain A； PDBConstruct 1–371； UniProt 1–371 Author chain B； PDBConstruct 1–371； UniProt 1–371

Maltose-binding periplasmic protein

Escherichia coli

UniProt P0AEX9

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Other combination	Heteromer	Protein 5 其他Polymer 1	Maltose/maltodextrin import ATP-binding protein malK × 2 （Q1R3Q1） Maltose transport system permease protein malF × 1 （P02916） Maltose transport system permease protein malG × 1 （P68183） alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose × 1 ADENOSINE-5'-TRIPHOSPHATE × 2	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	MALE_ECOLI
Isoform	—
PDB entities	2
Chains and sequence ranges	Author chain E； PDBConstruct 1–370； UniProt 27–396

Maltose transport system permease protein malF

Escherichia coli

UniProt P02916

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Other combination	Heteromer	Protein 5 其他Polymer 1	Maltose/maltodextrin import ATP-binding protein malK × 2 （Q1R3Q1） Maltose-binding periplasmic protein × 1 （P0AEX9） Maltose transport system permease protein malG × 1 （P68183） alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose × 1 ADENOSINE-5'-TRIPHOSPHATE × 2	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	MALF_ECOLI
Isoform	—
PDB entities	3
Chains and sequence ranges	Author chain F； PDBConstruct 1–514； UniProt 1–514

Maltose transport system permease protein malG

Escherichia coli

UniProt P68183

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Other combination	Heteromer	Protein 5 其他Polymer 1	Maltose/maltodextrin import ATP-binding protein malK × 2 （Q1R3Q1） Maltose-binding periplasmic protein × 1 （P0AEX9） Maltose transport system permease protein malF × 1 （P02916） alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose × 1 ADENOSINE-5'-TRIPHOSPHATE × 2	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	MALG_ECOLI
Isoform	—
PDB entities	4
Chains and sequence ranges	Author chain G； PDBConstruct 1–296； UniProt 1–296

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	2r6g
Deposition date deposition_date	2007-09-05
Structure title title	The Crystal Structure of the E. coli Maltose Transporter
Keywords keywords	;ABC transporter, catalytic intermediate, E. coli maltose transporter, MBP, maltodextrin binding protein, MalK, ATP binding cassette, ATP-binding, Hydrolase, Inner membrane, Membrane, Nucleotide-binding, Sugar transport, Transmembrane, HYDROLASE-TRANSPORT PROTEIN COMPLEX ;; HYDROLASE/TRANSPORT 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.

2r6g__assembly_1__model_1

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

Download this curve (.dat)

2r6g__assembly_1__model_1 | I(q)

100 plotted points; both axes use logarithmic scales.

2r6g__assembly_1__model_1 | P(r) · Pending

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

Rg（Guinier）	48.40 Å
Rg (electron density)	48.20 Å
Total Rg	48.18 Å
Atom count	14713
Residues	1887
Excluded volume	265180 Å³
Maximum q	0.500 Å⁻¹

Assembly	Model	Structure unit	Oligomeric description	Status	CRYSOL	Actions
1	1	`2r6g__assembly_1__model_1`	pentameric （5）	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 (6)

Entity 1 Entity 1 polymer

Description description	Maltose/maltodextrin import ATP-binding protein malK
Molecular weight formula_weight	42183.6 kDa
EC 编号 ec_number	3.6.3.19
Mutation mutation	E159Q
Source method src_method	man
Copy count entity_count	2

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	A,B
Atom count atom_count	14713

MASVQLQNVTKAWGEVVVSKDINLDIHEGEFVVFVGPSGCGKSTLLRMIAGLETITSGDLFIGEKRMNDTPPAERGVGMVFQSYALYPHLSVAENMSFGLKLAGAKKEVINQRVNQVAEVLQLAHLLDRKPKALSGGQRQRVAIGRTLVAEPSVFLLDQPLSNLDAALRVQMRIEISRLHKRLGRTMIYVTHDQVEAMTLADKIVVLDAGRVAQVGKPLELYHYPADRFVAGFIGSPKMNFLPVKVTATAIDQVQVELPMPNRQQVWLPVESRDVQVGANMSLGIRPEHLLPSDIADVILEGEVQVVEQLGNETQIHIQIPSIRQNLVYRQNDVVLVEEGATFAIGLPPERCHLFREDGTACRRLHKEPGVASASHHHHHH

Source Source

Source organism organism	Escherichia coli
NCBI taxonomy ID ncbi_taxonomy_id	83333
Host organism host_organism	Escherichia coli

Entity 2 Entity 2 polymer

Description description	Maltose-binding periplasmic protein
Molecular weight formula_weight	40753.2 kDa
Source method src_method	man
Copy count entity_count	1

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	E

KIEEGKLVIWINGDKGYNGLAEVGKKFEKDTGIKVTVEHPDKLEEKFPQVAATGDGPDIIFWAHDRFGGYAQSGLLAEITPDKAFQDKLYPFTWDAVRYNGKLIAYPIAVEALSLIYNKDLLPNPPKTWEEIPALDKELKAKGKSALMFNLQEPYFTWPLIAADGGYAFKYENGKYDIKDVGVDNAGAKAGLTFLVDLIKNKHMNADTDYSIAEAAFNKGETAMTINGPWAWSNIDTSKVNYGVTVLPTFKGQPSKPFVGVLSAGINAASPNKELAKEFLENYLLTDEGLEAVNKDKPLGAVALKSYEEELAKDPRIAATMENAQKGEIMPNIPQMSAFWYAVRTAVINAASGRQTVDEALKDAQTRITK

Source Source

Source organism organism	Escherichia coli
NCBI taxonomy ID ncbi_taxonomy_id	83333
Host organism host_organism	Escherichia coli

Entity 3 Entity 3 polymer

Description description	Maltose transport system permease protein malF
Molecular weight formula_weight	57052.9 kDa
Source method src_method	man
Copy count entity_count	1

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	F

MDVIKKKHWWQSDALKWSVLGLLGLLVGYLVVLMYAQGEYLFAITTLILSSAGLYIFANRKAYAWRYVYPGMAGMGLFVLFPLVCTIAIAFTNYSSTNQLTFERAQEVLLDRSWQAGKTYNFGLYPAGDEWQLALSDGETGKNYLSDAFKFGGEQKLQLKETTAQPEGERANLRVITQNRQALSDITAILPDGNKVMMSSLRQFSGTQPLYTLDGDGTLTNNQSGVKYRPNNQIGFYQSITADGNWGDEKLSPGYTVTTGWKNFTRVFTDEGIQKPFLAIFVWTVVFSLITVFLTVAVGMVLACLVQWEALRGKAVYRVLLILPYAVPSFISILIFKGLFNQSFGEINMMLSALFGVKPAWFSDPTTARTMLIIVNTWLGYPYMMILCMGLLKAIPDDLYEASAMDGAGPFQNFFKITLPLLIKPLTPLMIASFAFNFNNFVLIQLLTNGGPDRLGTTTPAGYTDLLVNYTYRIAFEGGGGQDFGLAAAIATLIFLLVGALAIVNLKATRMKFD

Source Source

Source organism organism	Escherichia coli
NCBI taxonomy ID ncbi_taxonomy_id	83333
Host organism host_organism	Escherichia coli

Entity 4 Entity 4 polymer

Description description	Maltose transport system permease protein malG
Molecular weight formula_weight	32246.2 kDa
Source method src_method	man
Copy count entity_count	1

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	G

MAMVQPKSQKARLFITHLLLLLFIAAIMFPLLMVVAISLRQGNFATGSLIPEQISWDHWKLALGFSVEQADGRITPPPFPVLLWLWNSVKVAGISAIGIVALSTTCAYAFARMRFPGKATLLKGMLIFQMFPAVLSLVALYALFDRLGEYIPFIGLNTHGGVIFAYLGGIALHVWTIKGYFETIDSSLEEAAALDGATPWQAFRLVLLPLSVPILAVVFILSFIAAITEVPVASLLLRDVNSYTLAVGMQQYLNPQNYLWGDFAAAAVMSALPITIVFLLAQRWLVNGLTAGGVKG

Source Source

Source organism organism	Escherichia coli
NCBI taxonomy ID ncbi_taxonomy_id	83333
Host organism host_organism	Escherichia coli

Entity 5 Entity 5 branched

Description description	alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose
Molecular weight formula_weight	342.3 kDa
Source method src_method	man
Copy count entity_count	1

Entity 6 Entity 6 non-polymer

Description description	ADENOSINE-5'-TRIPHOSPHATE
Molecular weight formula_weight	507.2 kDa
Source method src_method	syn
Copy count entity_count	2

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6. Fold Classification (SCOP + CATH) 23 domains

SCOP 2.08 (10 domains)

Domain ID domain_id	d2r6ga1
Class class	b — All beta proteins
Fold Fold fold	b.40 — OB-fold
Superfamily Superfamily superfamily	b.40.6 — MOP-like
Family Family family	b.40.6.3 — ABC-transporter additional domain

Domain ID domain_id	d2r6ga2
Class class	c — Alpha and beta proteins (a/b)
Fold Fold fold	c.37 — P-loop containing nucleoside triphosphate hydrolases
Superfamily Superfamily superfamily	c.37.1 — P-loop containing nucleoside triphosphate hydrolases
Family Family family	c.37.1.12 — ABC transporter ATPase domain-like

Domain ID domain_id	d2r6ga3
Class class	l — Artifacts
Fold Fold fold	l.1 — Tags
Superfamily Superfamily superfamily	l.1.1 — Tags
Family Family family	l.1.1.1 — Tags

Domain ID domain_id	d2r6gb1
Class class	b — All beta proteins
Fold Fold fold	b.40 — OB-fold
Superfamily Superfamily superfamily	b.40.6 — MOP-like
Family Family family	b.40.6.3 — ABC-transporter additional domain

Domain ID domain_id	d2r6gb2
Class class	c — Alpha and beta proteins (a/b)
Fold Fold fold	c.37 — P-loop containing nucleoside triphosphate hydrolases
Superfamily Superfamily superfamily	c.37.1 — P-loop containing nucleoside triphosphate hydrolases
Family Family family	c.37.1.12 — ABC transporter ATPase domain-like

Domain ID domain_id	d2r6gb3
Class class	l — Artifacts
Fold Fold fold	l.1 — Tags
Superfamily Superfamily superfamily	l.1.1 — Tags
Family Family family	l.1.1.1 — Tags

Domain ID domain_id	d2r6ge_
Class class	c — Alpha and beta proteins (a/b)
Fold Fold fold	c.94 — Periplasmic binding protein-like II
Superfamily Superfamily superfamily	c.94.1 — Periplasmic binding protein-like II
Family Family family	c.94.1.1 — Phosphate binding protein-like

Domain ID domain_id	d2r6gf1
Class class	e — Multi-domain proteins (alpha and beta)
Fold Fold fold	e.70 — MalF N-terminal region-like
Superfamily Superfamily superfamily	e.70.1 — MalF N-terminal region-like
Family Family family	e.70.1.1 — MalF N-terminal region-like

Domain ID domain_id	d2r6gf2
Class class	f — Membrane and cell surface proteins and peptides
Fold Fold fold	f.58 — MetI-like
Superfamily Superfamily superfamily	f.58.1 — MetI-like
Family Family family	f.58.1.1 — MetI-like

Domain ID domain_id	d2r6gg1
Class class	f — Membrane and cell surface proteins and peptides
Fold Fold fold	f.58 — MetI-like
Superfamily Superfamily superfamily	f.58.1 — MetI-like
Family Family family	f.58.1.1 — MetI-like

CATH v4.4 (13 domains)

Domain ID domain_id	2r6gA01
Class class	3 — Alpha Beta
Architecture architecture	40 — 3-Layer(aba) Sandwich
Topology topology	50 — Rossmann fold
Homologous superfamily homologous superfamily	300 — P-loop containing nucleotide triphosphate hydrolases

Domain ID domain_id	2r6gA02
Class class	2 — Mainly Beta
Architecture architecture	40 — Beta Barrel
Topology topology	50 — OB fold (Dihydrolipoamide Acetyltransferase, E2P)
Homologous superfamily homologous superfamily	100 — RNA polymerase II/Efflux pump adaptor protein, barrel-sandwich hybrid domain

Domain ID domain_id	2r6gA03
Class class	2 — Mainly Beta
Architecture architecture	40 — Beta Barrel
Topology topology	50 — OB fold (Dihydrolipoamide Acetyltransferase, E2P)
Homologous superfamily homologous superfamily	140 — Nucleic acid-binding proteins

Domain ID domain_id	2r6gB01
Class class	3 — Alpha Beta
Architecture architecture	40 — 3-Layer(aba) Sandwich
Topology topology	50 — Rossmann fold
Homologous superfamily homologous superfamily	300 — P-loop containing nucleotide triphosphate hydrolases

Domain ID domain_id	2r6gB02
Class class	2 — Mainly Beta
Architecture architecture	40 — Beta Barrel
Topology topology	50 — OB fold (Dihydrolipoamide Acetyltransferase, E2P)
Homologous superfamily homologous superfamily	100 — RNA polymerase II/Efflux pump adaptor protein, barrel-sandwich hybrid domain

Domain ID domain_id	2r6gB03
Class class	2 — Mainly Beta
Architecture architecture	40 — Beta Barrel
Topology topology	50 — OB fold (Dihydrolipoamide Acetyltransferase, E2P)
Homologous superfamily homologous superfamily	140 — Nucleic acid-binding proteins

Domain ID domain_id	2r6gE01
Class class	3 — Alpha Beta
Architecture architecture	40 — 3-Layer(aba) Sandwich
Topology topology	190 — D-Maltodextrin-Binding Protein; domain 2
Homologous superfamily homologous superfamily	10 — Periplasmic binding protein-like II

Domain ID domain_id	2r6gE02
Class class	3 — Alpha Beta
Architecture architecture	40 — 3-Layer(aba) Sandwich
Topology topology	190 — D-Maltodextrin-Binding Protein; domain 2
Homologous superfamily homologous superfamily	10 — Periplasmic binding protein-like II

Domain ID domain_id	2r6gF01
Class class	1 — Mainly Alpha
Architecture architecture	20 — Up-down Bundle
Topology topology	58 — Methane Monooxygenase Hydroxylase; Chain G, domain 1
Homologous superfamily homologous superfamily	370 — MalF N-terminal region-like

Domain ID domain_id	2r6gF02
Class class	3 — Alpha Beta
Architecture architecture	10 — Roll
Topology topology	650 — MalF N-terminal region-like
Homologous superfamily homologous superfamily	10 — MalF N-terminal region-like

Domain ID domain_id	2r6gF03
Class class	2 — Mainly Beta
Architecture architecture	40 — Beta Barrel
Topology topology	430 — Periplasmic binding protein-like II
Homologous superfamily homologous superfamily	10 — D-maltodextrin-binding protein, MBP

Domain ID domain_id	2r6gF04
Class class	1 — Mainly Alpha
Architecture architecture	10 — Orthogonal Bundle
Topology topology	3720 — MetI-like fold
Homologous superfamily homologous superfamily	10 — MetI-like

Domain ID domain_id	2r6gG01
Class class	1 — Mainly Alpha
Architecture architecture	10 — Orthogonal Bundle
Topology topology	3720 — MetI-like fold
Homologous superfamily homologous superfamily	10 — MetI-like

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Unit-cell length a length_a	73.260 Å
Unit-cell length b length_b	95.860 Å
Unit-cell length c length_c	109.990 Å
Unit-cell angle α angle_alpha	87.13 °
Unit-cell angle β angle_beta	82.43 °
Unit-cell angle γ angle_gamma	75.75 °
Molecules per unit cell Z z_pdb	2

Space group space_group	P 1
Space-group number int_tables_number	1
Crystal system crystal_system	—

Resolution resolution	2.800 Å
Low-resolution limit resolution_low	47.400 Å
R factor r_factor	0.2422
R_work r_work	0.2416
R_free r_free	0.2714

The Crystal Structure of the E. coli Maltose Transporter

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

Maltose/maltodextrin import ATP-binding protein malK

State in the Current Structure

Other States of the Same Protein in the Database

Monomer

Homodimer

Homotetramer

Other homooligomers

Heteromeric or nucleic-acid complex

Maltose-binding periplasmic protein

State in the Current Structure

Other States of the Same Protein in the Database

Monomer

Homodimer

Homotetramer

Other homooligomers

Heteromeric or nucleic-acid complex

Maltose transport system permease protein malF

State in the Current Structure

Other States of the Same Protein in the Database

Monomer

Homodimer

Homotetramer

Other homooligomers

Heteromeric or nucleic-acid complex

Maltose transport system permease protein malG

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

2r6g__assembly_1__model_1

2r6g__assembly_1__model_1 | I(q)

2r6g__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 (6)

Entity 1 Entity 1 polymer

Polymer Polymer

Source Source

Entity 2 Entity 2 polymer

Polymer Polymer

Source Source

Entity 3 Entity 3 polymer

Polymer Polymer

Source Source

Entity 4 Entity 4 polymer

Polymer Polymer

Source Source

Entity 5 Entity 5 branched

Entity 6 Entity 6 non-polymer

6. Fold Classification (SCOP + CATH) 23 domains

SCOP 2.08 (10 domains)

CATH v4.4 (13 domains)

7. Citations (1)