SAXSdb — 1hk9

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

PROTEIN HFQ

ESCHERICHIA COLI

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein homooligomer	Homooligomer	Protein 6	water × 6	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	HFQ_ECOLI
Isoform	—
PDB entities	1
Chains and sequence ranges	Author chain A； PDBConstruct 3–74； UniProt 1–72 Author chain B； PDBConstruct 3–74； UniProt 1–72 Author chain C； PDBConstruct 3–74； UniProt 1–72 Author chain D； PDBConstruct 3–74； UniProt 1–72 Author chain E； PDBConstruct 3–74； UniProt 1–72 Author chain F； PDBConstruct 3–74； UniProt 1–72

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	1hk9
Deposition date deposition_date	2003-03-06
Structure title title	Crystal structure of the Hfq protein from Escherichia coli
Keywords keywords	RNA-BINDING PROTEIN, SM-LIKE, PLEIOTROPIC REGULATOR, RNA BINDING PROTEIN, RNA CHAPERONE; RNA BINDING 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.

1hk9__assembly_1__model_1

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

Download this curve (.dat)

1hk9__assembly_1__model_1 | I(q)

100 plotted points; both axes use logarithmic scales.

1hk9__assembly_1__model_1 | P(r) · Pending

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

Rg（Guinier）	23.95 Å
Rg (electron density)	22.48 Å
Total Rg	23.43 Å
Atom count	3104
Residues	394
Excluded volume	56150 Å³
Maximum q	0.500 Å⁻¹

Assembly	Model	Structure unit	Oligomeric description	Status	CRYSOL	Actions
1	1	`1hk9__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 (2)

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6. Fold Classification (SCOP + CATH) 12 domains

SCOP 2.08 (6 domains)

Domain ID domain_id	d1hk9a_
Class class	b — All beta proteins
Fold Fold fold	b.38 — Sm-like fold
Superfamily Superfamily superfamily	b.38.1 — Sm-like ribonucleoproteins
Family Family family	b.38.1.2 — Pleiotropic translational regulator Hfq

Domain ID domain_id	d1hk9b_
Class class	b — All beta proteins
Fold Fold fold	b.38 — Sm-like fold
Superfamily Superfamily superfamily	b.38.1 — Sm-like ribonucleoproteins
Family Family family	b.38.1.2 — Pleiotropic translational regulator Hfq

Domain ID domain_id	d1hk9c_
Class class	b — All beta proteins
Fold Fold fold	b.38 — Sm-like fold
Superfamily Superfamily superfamily	b.38.1 — Sm-like ribonucleoproteins
Family Family family	b.38.1.2 — Pleiotropic translational regulator Hfq

Domain ID domain_id	d1hk9d_
Class class	b — All beta proteins
Fold Fold fold	b.38 — Sm-like fold
Superfamily Superfamily superfamily	b.38.1 — Sm-like ribonucleoproteins
Family Family family	b.38.1.2 — Pleiotropic translational regulator Hfq

Domain ID domain_id	d1hk9e_
Class class	b — All beta proteins
Fold Fold fold	b.38 — Sm-like fold
Superfamily Superfamily superfamily	b.38.1 — Sm-like ribonucleoproteins
Family Family family	b.38.1.2 — Pleiotropic translational regulator Hfq

Domain ID domain_id	d1hk9f_
Class class	b — All beta proteins
Fold Fold fold	b.38 — Sm-like fold
Superfamily Superfamily superfamily	b.38.1 — Sm-like ribonucleoproteins
Family Family family	b.38.1.2 — Pleiotropic translational regulator Hfq

CATH v4.4 (6 domains)

Domain ID domain_id	1hk9A00
Class class	2 — Mainly Beta
Architecture architecture	30 — Roll
Topology topology	30 — SH3 type barrels.
Homologous superfamily homologous superfamily	100 —

Domain ID domain_id	1hk9B00
Class class	2 — Mainly Beta
Architecture architecture	30 — Roll
Topology topology	30 — SH3 type barrels.
Homologous superfamily homologous superfamily	100 —

Domain ID domain_id	1hk9C00
Class class	2 — Mainly Beta
Architecture architecture	30 — Roll
Topology topology	30 — SH3 type barrels.
Homologous superfamily homologous superfamily	100 —

Domain ID domain_id	1hk9D00
Class class	2 — Mainly Beta
Architecture architecture	30 — Roll
Topology topology	30 — SH3 type barrels.
Homologous superfamily homologous superfamily	100 —

Domain ID domain_id	1hk9E00
Class class	2 — Mainly Beta
Architecture architecture	30 — Roll
Topology topology	30 — SH3 type barrels.
Homologous superfamily homologous superfamily	100 —

Domain ID domain_id	1hk9F00
Class class	2 — Mainly Beta
Architecture architecture	30 — Roll
Topology topology	30 — SH3 type barrels.
Homologous superfamily homologous superfamily	100 —

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7. Citations (6)

Sm-Like Proteins in Eubacteria: The Crystal Structure of the Hfq Protein from Escherichia Coli

Nucleic Acids Res. (2003)

PMID: 12853626 · DOI: 10.1093/NAR/GKG480 PRIMARY

The Sm-Like Hfq Protein Increases Oxys RNA Interaction with Target Mrnas

Mol.Cell (2002)

PMID: 11804582 · DOI: 10.1016/S1097-2765(01)00437-3

Hfq: A Bacterial Sm-Like Protein that Mediates RNA-RNA Interaction

Mol.Cell (2002)

PMID: 11804583 · DOI: 10.1016/S1097-2765(01)00436-1

Structures of the Pleiotropic Translational Regulator Hfq and an Hfq-RNA Complex: A Bacterial Sm-Like Protein

Embo J. (2002)

PMID: 12093755 · DOI: 10.1093/EMBOJ/CDF322

Characterization of Broadly Pleiotropic Phenotypes Caused by an Hfq Insertion Mutation in Escherichia Coli K-12

Mol.Microbiol. (1994)

PMID: 7984093 · DOI: 10.1111/J.1365-2958.1994.TB00400.X

;Bacterial Proteins Required for Replication of Phage Q Ribonucleic Acid. Purification and Properties of Host Factor I, a Ribonucleic Acid-Binding Protein ;

J.Biol.Chem. (1972)

PMID: 4550762

Unit-cell length a length_a	61.350 Å
Unit-cell length b length_b	61.350 Å
Unit-cell length c length_c	166.100 Å
Unit-cell angle α angle_alpha	90.00 °
Unit-cell angle β angle_beta	90.00 °
Unit-cell angle γ angle_gamma	120.00 °
Molecules per unit cell Z z_pdb	36

Space group space_group	P 61
Space-group number int_tables_number	169
Crystal system crystal_system	—

Resolution resolution	2.150 Å
Low-resolution limit resolution_low	20.000 Å
R factor r_factor	0.2080
R_work r_work	0.2080
R_free r_free	0.2620

Description description	PROTEIN HFQ
Molecular weight formula_weight	8257.6 kDa
Source method src_method	man
Copy count entity_count	6

Polymer type type	polypeptide(L)
Chain IDs strand_id	A,B,C,D,E,F
Atom count atom_count	3240

Crystal structure of the Hfq protein from Escherichia coli

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

PROTEIN HFQ

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

1hk9__assembly_1__model_1

1hk9__assembly_1__model_1 | I(q)

1hk9__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 (2)

Entity 1 Entity 1 polymer

Polymer Polymer

Source Source

Entity 2 Entity 2 water

6. Fold Classification (SCOP + CATH) 12 domains

SCOP 2.08 (6 domains)

CATH v4.4 (6 domains)

7. Citations (6)

Source organism organism	ESCHERICHIA COLI
NCBI taxonomy ID ncbi_taxonomy_id	562
Host organism host_organism	ESCHERICHIA COLI

Description description	water
Molecular weight formula_weight	18.0 kDa
Source method src_method	nat
Copy count entity_count	136

Crystal structure of the Hfq protein from Escherichia coli

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

PROTEIN HFQ

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

1hk9__assembly_1__model_1

1hk9__assembly_1__model_1 | I(q)

1hk9__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 (2)

Entity 1 Entity 1 polymer

Polymer Polymer

Source Source

Entity 2 Entity 2 water

6. Fold Classification (SCOP + CATH) 12 domains

SCOP 2.08 (6 domains)

CATH v4.4 (6 domains)

7. Citations (6)