1kq1

1.55 A Crystal structure of the pleiotropic translational regulator, Hfq

Method: X-RAY DIFFRACTION

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

Host Factor for Q beta

Staphylococcus aureus

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein homooligomer	Homooligomer	Protein 6	ACETIC ACID × 3 water × 6	Consistent with protein count
2	Protein homooligomer	Homooligomer	Protein 6	ACETIC ACID × 2 water × 6	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	Q99UG9_STAAM
Isoform	—
PDB entities	1
Chains and sequence ranges	Author chain A； PDBConstruct 1–77； UniProt 1–77 Author chain B； PDBConstruct 1–77； UniProt 1–77 Author chain H； PDBConstruct 1–77； UniProt 1–77 Author chain I； PDBConstruct 1–77； UniProt 1–77 Author chain K； PDBConstruct 1–77； UniProt 1–77 Author chain M； PDBConstruct 1–77； UniProt 1–77 Author chain N； PDBConstruct 1–77； UniProt 1–77 Author chain R； PDBConstruct 1–77； UniProt 1–77 Author chain S； PDBConstruct 1–77； UniProt 1–77 Author chain T； PDBConstruct 1–77； UniProt 1–77 Author chain W； PDBConstruct 1–77； UniProt 1–77 Author chain Y； PDBConstruct 1–77； UniProt 1–77

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	1kq1
Deposition date deposition_date	2002-01-03
Structure title title	1.55 A Crystal structure of the pleiotropic translational regulator, Hfq
Keywords keywords	Hfq, hexamer, RNA binding protein, translational regulator, Sm motif, TRANSLATION; TRANSLATION
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.

1kq1__assembly_1__model_1

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

Download this curve (.dat)

1kq1__assembly_1__model_1 | I(q)

100 plotted points; both axes use logarithmic scales.

1kq1__assembly_1__model_1 | P(r) · Pending

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

Rg（Guinier）	23.39 Å
Rg (electron density)	21.92 Å
Total Rg	22.96 Å
Atom count	3026
Residues	369
Excluded volume	54082 Å³
Maximum q	0.500 Å⁻¹

Assembly	Model	Structure unit	Oligomeric description	Status	CRYSOL	Actions
1	1	`1kq1__assembly_1__model_1`	hexameric （6）	Success	4.1.3-1-20251215 (887e7ef)	View Download
2	1	`1kq1__assembly_2__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 (3)

Entity 1 Entity 1 polymer

Description description	Host Factor for Q beta
Molecular weight formula_weight	8786.7 kDa
Source method src_method	man
Copy count entity_count	12

Polymer Polymer

Polymer type type	polypeptide(L)
Chain IDs strand_id	A,B,H,I,K,M,S,T,Y,N,R,W
Atom count atom_count	6611

MIANENIQDKALENFKANQTEVTVFFLNGFQMKGVIEEYDKYVVSLNSQGKQHLIYKHAISTYTVETEGQASTESEE

Source Source

Source organism organism	Staphylococcus aureus
NCBI taxonomy ID ncbi_taxonomy_id	1280
Host organism host_organism	Escherichia coli

Entity 2 Entity 2 non-polymer

Description description	ACETIC ACID
Molecular weight formula_weight	60.1 kDa
Source method src_method	syn
Copy count entity_count	5

Entity 3 Entity 3 water

Description description	water
Molecular weight formula_weight	18.0 kDa
Source method src_method	nat
Copy count entity_count	592

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6. Fold Classification (SCOP + CATH) 24 domains

SCOP 2.08 (12 domains)

Domain ID domain_id	d1kq1a_
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	d1kq1b_
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	d1kq1h_
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	d1kq1i_
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	d1kq1k_
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	d1kq1m_
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	d1kq1n_
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	d1kq1r_
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	d1kq1s_
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	d1kq1t_
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	d1kq1w_
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	d1kq1y_
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 (12 domains)

Domain ID domain_id	1kq1A00
Class class	2 — Mainly Beta
Architecture architecture	30 — Roll
Topology topology	30 — SH3 type barrels.
Homologous superfamily homologous superfamily	100 —

Domain ID domain_id	1kq1B00
Class class	2 — Mainly Beta
Architecture architecture	30 — Roll
Topology topology	30 — SH3 type barrels.
Homologous superfamily homologous superfamily	100 —

Domain ID domain_id	1kq1H00
Class class	2 — Mainly Beta
Architecture architecture	30 — Roll
Topology topology	30 — SH3 type barrels.
Homologous superfamily homologous superfamily	100 —

Domain ID domain_id	1kq1I00
Class class	2 — Mainly Beta
Architecture architecture	30 — Roll
Topology topology	30 — SH3 type barrels.
Homologous superfamily homologous superfamily	100 —

Domain ID domain_id	1kq1K00
Class class	2 — Mainly Beta
Architecture architecture	30 — Roll
Topology topology	30 — SH3 type barrels.
Homologous superfamily homologous superfamily	100 —

Domain ID domain_id	1kq1M00
Class class	2 — Mainly Beta
Architecture architecture	30 — Roll
Topology topology	30 — SH3 type barrels.
Homologous superfamily homologous superfamily	100 —

Domain ID domain_id	1kq1N00
Class class	2 — Mainly Beta
Architecture architecture	30 — Roll
Topology topology	30 — SH3 type barrels.
Homologous superfamily homologous superfamily	100 —

Domain ID domain_id	1kq1R00
Class class	2 — Mainly Beta
Architecture architecture	30 — Roll
Topology topology	30 — SH3 type barrels.
Homologous superfamily homologous superfamily	100 —

Domain ID domain_id	1kq1S00
Class class	2 — Mainly Beta
Architecture architecture	30 — Roll
Topology topology	30 — SH3 type barrels.
Homologous superfamily homologous superfamily	100 —

Domain ID domain_id	1kq1T00
Class class	2 — Mainly Beta
Architecture architecture	30 — Roll
Topology topology	30 — SH3 type barrels.
Homologous superfamily homologous superfamily	100 —

Domain ID domain_id	1kq1W00
Class class	2 — Mainly Beta
Architecture architecture	30 — Roll
Topology topology	30 — SH3 type barrels.
Homologous superfamily homologous superfamily	100 —

Domain ID domain_id	1kq1Y00
Class class	2 — Mainly Beta
Architecture architecture	30 — Roll
Topology topology	30 — SH3 type barrels.
Homologous superfamily homologous superfamily	100 —

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Unit-cell length a length_a	67.030 Å
Unit-cell length b length_b	89.950 Å
Unit-cell length c length_c	67.770 Å
Unit-cell angle α angle_alpha	90.00 °
Unit-cell angle β angle_beta	97.95 °
Unit-cell angle γ angle_gamma	90.00 °
Molecules per unit cell Z z_pdb	24

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

Resolution resolution	1.550 Å
Low-resolution limit resolution_low	22.370 Å
R factor r_factor	—
R_work r_work	0.2370
R_free r_free	0.2590

1.55 A Crystal structure of the pleiotropic translational regulator, Hfq

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

Host Factor for Q beta

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

1kq1__assembly_1__model_1

1kq1__assembly_1__model_1 | I(q)

1kq1__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 (3)

Entity 1 Entity 1 polymer

Polymer Polymer

Source Source

Entity 2 Entity 2 non-polymer

Entity 3 Entity 3 water

6. Fold Classification (SCOP + CATH) 24 domains

SCOP 2.08 (12 domains)

CATH v4.4 (12 domains)

7. Citations (1)

1.55 A Crystal structure of the pleiotropic translational regulator, Hfq

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

Host Factor for Q beta

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

1kq1__assembly_1__model_1

1kq1__assembly_1__model_1 | I(q)

1kq1__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 (3)

Entity 1 Entity 1 polymer

Polymer Polymer

Source Source

Entity 2 Entity 2 non-polymer

Entity 3 Entity 3 water

6. Fold Classification (SCOP + CATH) 24 domains

SCOP 2.08 (12 domains)

CATH v4.4 (12 domains)

7. Citations (1)