1qlb

respiratory complex II-like fumarate reductase from Wolinella succinogenes

Method: X-RAY DIFFRACTION

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

FUMARATE REDUCTASE FLAVOPROTEIN SUBUNIT

OrganismNot specified

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein heterocomplex	Heteromer	Protein 6	FUMARATE REDUCTASE IRON-SULFUR PROTEIN × 2 （P17596） FUMARATE REDUCTASE CYTOCHROME B SUBUNIT × 2 （P17413） FLAVIN-ADENINE DINUCLEOTIDE × 2 FUMARIC ACID × 2 CALCIUM ION × 2 FE2/S2 (INORGANIC) CLUSTER × 2 FE3-S4 CLUSTER × 2 IRON/SULFUR CLUSTER × 2 PROTOPORPHYRIN IX CONTAINING FE × 4 DODECYL-BETA-D-MALTOSIDE × 2 water × 6	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	FRDA_WOLSU
Isoform	—
PDB entities	1
Chains and sequence ranges	Author chain A； PDBConstruct 1–656； UniProt 1–656 Author chain D； PDBConstruct 1–656； UniProt 1–656

FUMARATE REDUCTASE IRON-SULFUR PROTEIN

OrganismNot specified

UniProt P17596

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein heterocomplex	Heteromer	Protein 6	FUMARATE REDUCTASE FLAVOPROTEIN SUBUNIT × 2 （P17412） FUMARATE REDUCTASE CYTOCHROME B SUBUNIT × 2 （P17413） FLAVIN-ADENINE DINUCLEOTIDE × 2 FUMARIC ACID × 2 CALCIUM ION × 2 FE2/S2 (INORGANIC) CLUSTER × 2 FE3-S4 CLUSTER × 2 IRON/SULFUR CLUSTER × 2 PROTOPORPHYRIN IX CONTAINING FE × 4 DODECYL-BETA-D-MALTOSIDE × 2 water × 6	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	FRDB_WOLSU
Isoform	—
PDB entities	2
Chains and sequence ranges	Author chain B； PDBConstruct 1–239； UniProt 1–239 Author chain E； PDBConstruct 1–239； UniProt 1–239

FUMARATE REDUCTASE CYTOCHROME B SUBUNIT

OrganismNot specified

UniProt P17413

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein heterocomplex	Heteromer	Protein 6	FUMARATE REDUCTASE FLAVOPROTEIN SUBUNIT × 2 （P17412） FUMARATE REDUCTASE IRON-SULFUR PROTEIN × 2 （P17596） FLAVIN-ADENINE DINUCLEOTIDE × 2 FUMARIC ACID × 2 CALCIUM ION × 2 FE2/S2 (INORGANIC) CLUSTER × 2 FE3-S4 CLUSTER × 2 IRON/SULFUR CLUSTER × 2 PROTOPORPHYRIN IX CONTAINING FE × 4 DODECYL-BETA-D-MALTOSIDE × 2 water × 6	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	FRDC_WOLSU
Isoform	—
PDB entities	3
Chains and sequence ranges	Author chain C； PDBConstruct 1–256； UniProt 1–256 Author chain F； PDBConstruct 1–256； UniProt 1–256

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	1qlb
Deposition date deposition_date	1999-08-25
Structure title title	respiratory complex II-like fumarate reductase from Wolinella succinogenes
Keywords keywords	OXIDOREDUCTASE, CITRIC ACID CYCLE, RESPIRATORY CHAIN IRON-SULPHUR PROTEIN; OXIDOREDUCTASE
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.

1qlb__assembly_1__model_1

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

Download this curve (.dat)

1qlb__assembly_1__model_1 | I(q)

100 plotted points; both axes use logarithmic scales.

1qlb__assembly_1__model_1 | P(r) · Pending

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

Rg（Guinier）	43.83 Å
Rg (electron density)	43.75 Å
Total Rg	43.65 Å
Atom count	18552
Residues	2296
Excluded volume	331870 Å³
Maximum q	0.500 Å⁻¹

Assembly	Model	Structure unit	Oligomeric description	Status	CRYSOL	Actions
1	1	`1qlb__assembly_1__model_1`	hexameric （6）	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 (12)

Entity 1 Entity 1 polymer

Description description	FUMARATE REDUCTASE FLAVOPROTEIN SUBUNIT
Molecular weight formula_weight	72941.2 kDa
EC 编号 ec_number	1.3.99.1
Source method src_method	nat
Copy count entity_count	2

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	A,D
Atom count atom_count	19056

MKVQYCDSLVIGGGLAGLRAAVATQQKGLSTIVLSLIPVKRSHSAAAQGGMQASLGNSKMSDGDNEDLHFMDTVKGSDWGCDQKVARMFVNTAPKAIRELAAWGVPWTRIHKGDRMAIINAQKTTITEEDFRHGLIHSRDFGGTKKWRTCYTADATGHTMLFAVANECLKLGVSIQDRKEAIALIHQDGKCYGAVVRDLVTGDIIAYVAKGTLIATGGYGRIYKNTTNAVVCEGTGTAIALETGIAQLGNMEAVQFHPTPLFPSGILLTEGCRGDGGILRDVDGHRFMPDYEPEKKELASRDVVSRRMIEHIRKGKGVQSPYGQHLWLDISILGRKHIETNLRDVQEICEYFAGIDPAEKWAPVLPMQHYSMGGIRTDYRGEAKLKGLFSAGEAACWDMHGFNRLGGNSVSEAVVAGMIVGEYFAEHCANTQVDLETKTLEKFVKGQEAYMKSLVESKGTEDVFKIKNRMKDVMDDNVGIFRDGPHLEKSVKELEELYKKSKNVGIKNKRLHANPELEEAYRVPMMLKVALCVAKGALDRTESRGAHNREDYPKRDDINWLNRTLASWPNPEQTLPTLEYEALDVNEMEIAPRYRGYGAKGNYIENPLSVKRQEEIDKIQSELEAAGKDRHAIQEALMPYELPAKYKARNERLGDK

Entity 2 Entity 2 polymer

Description description	FUMARATE REDUCTASE IRON-SULFUR PROTEIN
Molecular weight formula_weight	27197.5 kDa
EC 编号 ec_number	1.3.99.1
Source method src_method	nat
Copy count entity_count	2

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	B,E

MGRMLTIRVFKYDPQSAVSKPHFQEYKIEEAPSMTIFIVLNMIRETYDPDLNFDFVCRAGICGSCGMMINGRPSLACRTLTKDFEDGVITLLPLPAFKLIKDLSVDTGNWFNGMSQRVESWIHAQKEHDISKLEERIEPEVAQEVFELDRCIECGCCIAACGTKIMREDFVGAAGLNRVVRFMIDPHDERTDEDYYELIGDDDGVFGCMTLLACHDVCPKNLPLQSKIAYLRRKMVSVN

Entity 3 Entity 3 polymer

Description description	FUMARATE REDUCTASE CYTOCHROME B SUBUNIT
Molecular weight formula_weight	29759.1 kDa
Source method src_method	nat
Copy count entity_count	2

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	C,F

MTNESILESYSGVTPERKKSRMPAKLDWWQSATGLFLGLFMIGHMFFVSTILLGDNVMLWVTKKFELDFIFEGGKPIVVSFLAAFVFAVFIAHAFLAMRKFPINYRQYLTFKTHKDLMRHGDTTLWWIQAMTGFAMFFLGSVHLYIMMTQPQTIGPVSSSFRMVSEWMWPLYLVLLFAVELHGSVGLYRLAVKWGWFDGETPDKTRANLKKLKTLMSAFLIVLGLLTFGAYVKKGLEQTDPNIDYKYFDYKRTHHR

Entity 4 Entity 4 non-polymer

Description description	FLAVIN-ADENINE DINUCLEOTIDE
Molecular weight formula_weight	785.5 kDa
Source method src_method	syn
Copy count entity_count	2

Entity 5 Entity 5 non-polymer

Description description	FUMARIC ACID
Molecular weight formula_weight	116.1 kDa
Source method src_method	syn
Copy count entity_count	2

Entity 6 Entity 6 non-polymer

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

Entity 7 Entity 7 non-polymer

Description description	FE2/S2 (INORGANIC) CLUSTER
Molecular weight formula_weight	175.8 kDa
Source method src_method	syn
Copy count entity_count	2

Entity 8 Entity 8 non-polymer

Description description	FE3-S4 CLUSTER
Molecular weight formula_weight	295.8 kDa
Source method src_method	syn
Copy count entity_count	2

Entity 9 Entity 9 non-polymer

Description description	IRON/SULFUR CLUSTER
Molecular weight formula_weight	351.6 kDa
Source method src_method	syn
Copy count entity_count	2

Entity 10 Entity 10 non-polymer

Description description	PROTOPORPHYRIN IX CONTAINING FE
Molecular weight formula_weight	616.5 kDa
Source method src_method	syn
Copy count entity_count	4

Entity 11 Entity 11 non-polymer

Description description	DODECYL-BETA-D-MALTOSIDE
Molecular weight formula_weight	510.6 kDa
Source method src_method	syn
Copy count entity_count	2

Entity 12 Entity 12 water

Description description	water
Molecular weight formula_weight	18.0 kDa
Source method src_method	nat
Copy count entity_count	504

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6. Fold Classification (SCOP + CATH) 26 domains

SCOP 2.08 (12 domains)

Domain ID domain_id	d1qlba1
Class class	a — All alpha proteins
Fold Fold fold	a.7 — Spectrin repeat-like
Superfamily Superfamily superfamily	a.7.3 — Succinate dehydrogenase/fumarate reductase flavoprotein C-terminal domain
Family Family family	a.7.3.1 — Succinate dehydrogenase/fumarate reductase flavoprotein C-terminal domain

Domain ID domain_id	d1qlba2
Class class	c — Alpha and beta proteins (a/b)
Fold Fold fold	c.3 — FAD/NAD(P)-binding domain
Superfamily Superfamily superfamily	c.3.1 — FAD/NAD(P)-binding domain
Family Family family	c.3.1.4 — Succinate dehydrogenase/fumarate reductase flavoprotein N-terminal domain

Domain ID domain_id	d1qlba3
Class class	d — Alpha and beta proteins (a+b)
Fold Fold fold	d.168 — Succinate dehydrogenase/fumarate reductase flavoprotein, catalytic domain
Superfamily Superfamily superfamily	d.168.1 — Succinate dehydrogenase/fumarate reductase flavoprotein, catalytic domain
Family Family family	d.168.1.1 — Succinate dehydrogenase/fumarate reductase flavoprotein, catalytic domain

Domain ID domain_id	d1qlbb1
Class class	a — All alpha proteins
Fold Fold fold	a.1 — Globin-like
Superfamily Superfamily superfamily	a.1.2 — alpha-helical ferredoxin
Family Family family	a.1.2.1 — Fumarate reductase/Succinate dehydogenase iron-sulfur protein, C-terminal domain

Domain ID domain_id	d1qlbb2
Class class	d — Alpha and beta proteins (a+b)
Fold Fold fold	d.15 — beta-Grasp (ubiquitin-like)
Superfamily Superfamily superfamily	d.15.4 — 2Fe-2S ferredoxin-like
Family Family family	d.15.4.2 — 2Fe-2S ferredoxin domains from multidomain proteins

Domain ID domain_id	d1qlbc_
Class class	f — Membrane and cell surface proteins and peptides
Fold Fold fold	f.21 — Heme-binding four-helical bundle
Superfamily Superfamily superfamily	f.21.2 — Fumarate reductase respiratory complex transmembrane subunits
Family Family family	f.21.2.1 — Fumarate reductase respiratory complex cytochrome b subunit, FrdC

Domain ID domain_id	d1qlbd1
Class class	a — All alpha proteins
Fold Fold fold	a.7 — Spectrin repeat-like
Superfamily Superfamily superfamily	a.7.3 — Succinate dehydrogenase/fumarate reductase flavoprotein C-terminal domain
Family Family family	a.7.3.1 — Succinate dehydrogenase/fumarate reductase flavoprotein C-terminal domain

Domain ID domain_id	d1qlbd2
Class class	c — Alpha and beta proteins (a/b)
Fold Fold fold	c.3 — FAD/NAD(P)-binding domain
Superfamily Superfamily superfamily	c.3.1 — FAD/NAD(P)-binding domain
Family Family family	c.3.1.4 — Succinate dehydrogenase/fumarate reductase flavoprotein N-terminal domain

Domain ID domain_id	d1qlbd3
Class class	d — Alpha and beta proteins (a+b)
Fold Fold fold	d.168 — Succinate dehydrogenase/fumarate reductase flavoprotein, catalytic domain
Superfamily Superfamily superfamily	d.168.1 — Succinate dehydrogenase/fumarate reductase flavoprotein, catalytic domain
Family Family family	d.168.1.1 — Succinate dehydrogenase/fumarate reductase flavoprotein, catalytic domain

Domain ID domain_id	d1qlbe1
Class class	a — All alpha proteins
Fold Fold fold	a.1 — Globin-like
Superfamily Superfamily superfamily	a.1.2 — alpha-helical ferredoxin
Family Family family	a.1.2.1 — Fumarate reductase/Succinate dehydogenase iron-sulfur protein, C-terminal domain

Domain ID domain_id	d1qlbe2
Class class	d — Alpha and beta proteins (a+b)
Fold Fold fold	d.15 — beta-Grasp (ubiquitin-like)
Superfamily Superfamily superfamily	d.15.4 — 2Fe-2S ferredoxin-like
Family Family family	d.15.4.2 — 2Fe-2S ferredoxin domains from multidomain proteins

Domain ID domain_id	d1qlbf_
Class class	f — Membrane and cell surface proteins and peptides
Fold Fold fold	f.21 — Heme-binding four-helical bundle
Superfamily Superfamily superfamily	f.21.2 — Fumarate reductase respiratory complex transmembrane subunits
Family Family family	f.21.2.1 — Fumarate reductase respiratory complex cytochrome b subunit, FrdC

CATH v4.4 (14 domains)

Domain ID domain_id	1qlbA01
Class class	3 — Alpha Beta
Architecture architecture	50 — 3-Layer(bba) Sandwich
Topology topology	50 — FAD/NAD(P)-binding domain
Homologous superfamily homologous superfamily	60 — FAD/NAD(P)-binding domain

Domain ID domain_id	1qlbA02
Class class	3 — Alpha Beta
Architecture architecture	90 — Alpha-Beta Complex
Topology topology	700 — Flavocytochrome C3; Chain A, domain 1
Homologous superfamily homologous superfamily	10 — Succinate dehydrogenase/fumarate reductase flavoprotein, catalytic domain

Domain ID domain_id	1qlbA03
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	100 — Fumarate reductase/succinate dehydrogenase flavoprotein-like, C-terminal domain

Domain ID domain_id	1qlbA04
Class class	3 — Alpha Beta
Architecture architecture	10 — Roll
Topology topology	20 — Ubiquitin-like (UB roll)
Homologous superfamily homologous superfamily	820 —

Domain ID domain_id	1qlbB01
Class class	3 — Alpha Beta
Architecture architecture	10 — Roll
Topology topology	20 — Ubiquitin-like (UB roll)
Homologous superfamily homologous superfamily	30 — Beta-grasp domain

Domain ID domain_id	1qlbB02
Class class	1 — Mainly Alpha
Architecture architecture	10 — Orthogonal Bundle
Topology topology	1060 — Fumarate Reductase Iron-sulfur Protein; Chain B, domain 2
Homologous superfamily homologous superfamily	10 — Alpha-helical ferredoxin

Domain ID domain_id	1qlbC00
Class class	1 — Mainly Alpha
Architecture architecture	20 — Up-down Bundle
Topology topology	1300 — 3 helical TM bundles of succinate and fumarate reductases
Homologous superfamily homologous superfamily	10 — Fumarate reductase/succinate dehydrogenase, transmembrane subunit

Domain ID domain_id	1qlbD01
Class class	3 — Alpha Beta
Architecture architecture	50 — 3-Layer(bba) Sandwich
Topology topology	50 — FAD/NAD(P)-binding domain
Homologous superfamily homologous superfamily	60 — FAD/NAD(P)-binding domain

Domain ID domain_id	1qlbD02
Class class	3 — Alpha Beta
Architecture architecture	90 — Alpha-Beta Complex
Topology topology	700 — Flavocytochrome C3; Chain A, domain 1
Homologous superfamily homologous superfamily	10 — Succinate dehydrogenase/fumarate reductase flavoprotein, catalytic domain

Domain ID domain_id	1qlbD03
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	100 — Fumarate reductase/succinate dehydrogenase flavoprotein-like, C-terminal domain

Domain ID domain_id	1qlbD04
Class class	3 — Alpha Beta
Architecture architecture	10 — Roll
Topology topology	20 — Ubiquitin-like (UB roll)
Homologous superfamily homologous superfamily	820 —

Domain ID domain_id	1qlbE01
Class class	3 — Alpha Beta
Architecture architecture	10 — Roll
Topology topology	20 — Ubiquitin-like (UB roll)
Homologous superfamily homologous superfamily	30 — Beta-grasp domain

Domain ID domain_id	1qlbE02
Class class	1 — Mainly Alpha
Architecture architecture	10 — Orthogonal Bundle
Topology topology	1060 — Fumarate Reductase Iron-sulfur Protein; Chain B, domain 2
Homologous superfamily homologous superfamily	10 — Alpha-helical ferredoxin

Domain ID domain_id	1qlbF00
Class class	1 — Mainly Alpha
Architecture architecture	20 — Up-down Bundle
Topology topology	1300 — 3 helical TM bundles of succinate and fumarate reductases
Homologous superfamily homologous superfamily	10 — Fumarate reductase/succinate dehydrogenase, transmembrane subunit

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Unit-cell length a length_a	118.400 Å
Unit-cell length b length_b	85.050 Å
Unit-cell length c length_c	188.850 Å
Unit-cell angle α angle_alpha	90.00 °
Unit-cell angle β angle_beta	96.46 °
Unit-cell angle γ angle_gamma	90.00 °
Molecules per unit cell Z z_pdb	4

Space group space_group	P 1 21 1
Space-group number int_tables_number	4
Crystal system crystal_system	—

Resolution resolution	2.330 Å
Low-resolution limit resolution_low	38.870 Å
R factor r_factor	0.2130
R_work r_work	0.2130
R_free r_free	0.2230

respiratory complex II-like fumarate reductase from Wolinella succinogenes

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

FUMARATE REDUCTASE FLAVOPROTEIN SUBUNIT

State in the Current Structure

Other States of the Same Protein in the Database

Monomer

Homodimer

Homotetramer

Other homooligomers

Heteromeric or nucleic-acid complex

FUMARATE REDUCTASE IRON-SULFUR 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

FUMARATE REDUCTASE CYTOCHROME B SUBUNIT

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

1qlb__assembly_1__model_1

1qlb__assembly_1__model_1 | I(q)

1qlb__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 (12)

Entity 1 Entity 1 polymer

Polymer Polymer

Entity 2 Entity 2 polymer

Polymer Polymer

Entity 3 Entity 3 polymer

Polymer 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 non-polymer

Entity 9 Entity 9 non-polymer

Entity 10 Entity 10 non-polymer

Entity 11 Entity 11 non-polymer

Entity 12 Entity 12 water

6. Fold Classification (SCOP + CATH) 26 domains

SCOP 2.08 (12 domains)

CATH v4.4 (14 domains)

7. Citations (1)