SAXSdb — 6ckk

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

N-acylneuraminate cytidylyltransferase

Neisseria meningitidis

State in the Current Structure

Assembly	Physical composition	Protein state	Molecular copy count	Associated components	Data consistency
1	Protein homooligomer	Homooligomer	Protein 2	CYTIDINE-5'-TRIPHOSPHATE × 2 CALCIUM ION × 3 water × 2	Consistent with protein count

Other States of the Same Protein in the Database

View Construct and Data Evidence

UniProt name	NEUA_NEIME
Isoform	—
PDB entities	1
Chains and sequence ranges	Author chain A； PDBConstruct 1–228； UniProt 1–228 Author chain B； PDBConstruct 1–228； UniProt 1–228

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	6ckk
Deposition date deposition_date	2018-02-28
Structure title title	N. meningitidis CMP-sialic acid synthetase in the presence of CTP and Ca2+
Keywords keywords	polysaccharide synthesis, sialic acid-activator, CMP-transferase, transferase; TRANSFERASE
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.

6ckk__assembly_1__model_1

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

Download this curve (.dat)

6ckk__assembly_1__model_1 | I(q)

100 plotted points; both axes use logarithmic scales.

6ckk__assembly_1__model_1 | P(r) · Pending

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

Rg（Guinier）	26.49 Å
Rg (electron density)	26.12 Å
Total Rg	26.80 Å
Atom count	3502
Residues	450
Excluded volume	62235 Å³
Maximum q	0.500 Å⁻¹

Assembly	Model	Structure unit	Oligomeric description	Status	CRYSOL	Actions
1	1	`6ckk__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 (4)

Entity 1 Entity 1 polymer

Description description	N-acylneuraminate cytidylyltransferase
Molecular weight formula_weight	24920.4 kDa
EC 编号 ec_number	2.7.7.43
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	4238

MEKQNIAVILARQNSKGLPLKNLRKMNGISLLGHTINAAISSKCFDRIIVSTDGGLIAEEAKNFGVEVVLRPAELASDTASSISGVIHALETIGSNSGTVTLLQPTSPLRTGAHIREAFSLFDEKIKGSVVSACPMEHHPLKTLLQINNGEYAPMRHLSDLEQPRQQLPQAFRPNGAIYINDTASLIANNCFFIAPTKLYIMSHQDSIDIDTELDLQQAENILNHKES

Source Source

Source organism organism	Neisseria meningitidis
NCBI taxonomy ID ncbi_taxonomy_id	487
Host organism host_organism	Escherichia coli

Entity 2 Entity 2 non-polymer

Description description	CYTIDINE-5'-TRIPHOSPHATE
Molecular weight formula_weight	483.2 kDa
Source method src_method	syn
Copy count entity_count	2

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	3

Entity 4 Entity 4 water

Description description	water
Molecular weight formula_weight	18.0 kDa
Source method src_method	nat
Copy count entity_count	680

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6. Fold Classification (SCOP + CATH) 4 domains

SCOP 2.08 (2 domains)

Domain ID domain_id	d6ckka_
Class class	c — Alpha and beta proteins (a/b)
Fold Fold fold	c.68 — Nucleotide-diphospho-sugar transferases
Superfamily Superfamily superfamily	c.68.1 — Nucleotide-diphospho-sugar transferases
Family Family family	c.68.1.13 — Cytidylytransferase

Domain ID domain_id	d6ckkb_
Class class	c — Alpha and beta proteins (a/b)
Fold Fold fold	c.68 — Nucleotide-diphospho-sugar transferases
Superfamily Superfamily superfamily	c.68.1 — Nucleotide-diphospho-sugar transferases
Family Family family	c.68.1.13 — Cytidylytransferase

CATH v4.4 (2 domains)

Domain ID domain_id	6ckkA00
Class class	3 — Alpha Beta
Architecture architecture	90 — Alpha-Beta Complex
Topology topology	550 — Spore Coat Polysaccharide Biosynthesis Protein SpsA; Chain A
Homologous superfamily homologous superfamily	10 — Spore Coat Polysaccharide Biosynthesis Protein SpsA; Chain A

Domain ID domain_id	6ckkB00
Class class	3 — Alpha Beta
Architecture architecture	90 — Alpha-Beta Complex
Topology topology	550 — Spore Coat Polysaccharide Biosynthesis Protein SpsA; Chain A
Homologous superfamily homologous superfamily	10 — Spore Coat Polysaccharide Biosynthesis Protein SpsA; Chain A

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Unit-cell length a length_a	43.190 Å
Unit-cell length b length_b	69.560 Å
Unit-cell length c length_c	158.210 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	8

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

Resolution resolution	1.800 Å
Low-resolution limit resolution_low	79.110 Å
R factor r_factor	0.2044
R_work r_work	0.2019
R_free r_free	0.2496

N. meningitidis CMP-sialic acid synthetase in the presence of CTP and Ca2+

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

N-acylneuraminate cytidylyltransferase

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

6ckk__assembly_1__model_1

6ckk__assembly_1__model_1 | I(q)

6ckk__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 (4)

Entity 1 Entity 1 polymer

Polymer Polymer

Source Source

Entity 2 Entity 2 non-polymer

Entity 3 Entity 3 non-polymer

Entity 4 Entity 4 water

6. Fold Classification (SCOP + CATH) 4 domains

SCOP 2.08 (2 domains)

CATH v4.4 (2 domains)

7. Citations (1)

N. meningitidis CMP-sialic acid synthetase in the presence of CTP and Ca2+

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

N-acylneuraminate cytidylyltransferase

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

6ckk__assembly_1__model_1

6ckk__assembly_1__model_1 | I(q)

6ckk__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 (4)

Entity 1 Entity 1 polymer

Polymer Polymer

Source Source

Entity 2 Entity 2 non-polymer

Entity 3 Entity 3 non-polymer

Entity 4 Entity 4 water

6. Fold Classification (SCOP + CATH) 4 domains

SCOP 2.08 (2 domains)

CATH v4.4 (2 domains)

7. Citations (1)