Reviewed, UniProtKB/Swiss-Prot Q56221 (NQO2_THET8)

Names and origin

Protein names

Recommended name:
    NADH-quinone oxidoreductase subunit 2
    EC=1.6.99.5
Alternative name(s):
    NADH dehydrogenase I chain 2
    NDH-1 subunit 2

Gene names

Name:	nqo2
Ordered Locus Names:	TTHA0088

Organism

Thermus thermophilus (strain HB8 / ATCC 27634 / DSM 579) [Complete proteome] [HAMAP]

Taxonomic identifier

300852 [NCBI]

Taxonomic lineage

Bacteria › Deinococcus-Thermus › Deinococci › Thermales › Thermaceae › Thermus

Protein attributes

Sequence length	181 AA.
Sequence status	Complete.
Sequence processing	The displayed sequence is further processed into a mature form.
Protein existence	Evidence at protein level.

General annotation (Comments)

Function	NDH-1 shuttles electrons from NADH, via FMN and iron-sulfur (Fe-S) centers, to quinones in the respiratory chain. The immediate electron acceptor for the enzyme in this species is menaquinone. Couples the redox reaction to proton translocation (for every two electrons transferred, four hydrogen ions are translocated across the cytoplasmic membrane), and thus conserves the redox energy in a proton gradient required for the synthesis of ATP.
Catalytic activity	NADH + quinone = NAD+ + quinol.
Cofactor	Binds 1 2Fe-2S cluster. This 2Fe-2S cluster is referred to as N1a.
Subunit structure	NDH-1 is composed of 15 different subunits, nqo1 to nqo15. The complex has a L-shaped structure, with the hydrophobic arm (subunits nqo7, nqo8 and nqo10 to nqo14) embedded in the membrane and the hydrophilic peripheral arm (subunits nqo1 to nqo6, nqo9 and nqo15) protruding into the bacterial cytoplasm. The hydrophilic domain contains all the redox centers. Ref.3 Ref.4
Subcellular location	Cell membrane; Peripheral membrane protein; Cytoplasmic side.
Domain	The subunit can be divided into two domains: an N-terminal four-helical bundle (residues 2 to 74) involved in interactions with subunits nqo1 and nqo3, and a thioredoxin-like C-terminal domain (residues 75 to 180) that coordinates the binuclear cluster N1a.
Sequence similarities	Belongs to the complex I 24 kDa subunit family.

Ontologies

Keywords
Cellular component	Cell membrane Membrane
Ligand	2Fe-2S Iron Iron-sulfur Metal-binding NAD
Molecular function	Oxidoreductase
PTM	Disulfide bond Quinone
Technical term	3D-structure Complete proteome Direct protein sequencing
Gene Ontology (GO)
Biological process	oxidation reduction Inferred from electronic annotation. Source: UniProtKB-KW
Cellular component	extrinsic to membrane Inferred from electronic annotation. Source: UniProtKB-SubCell plasma membrane Inferred from electronic annotation. Source: UniProtKB-KW
Molecular function	2 iron, 2 sulfur cluster binding Inferred from electronic annotation. Source: UniProtKB-KW NAD or NADH binding Inferred from electronic annotation. Source: InterPro NADH dehydrogenase (quinone) activity Inferred from electronic annotation. Source: EC iron ion binding Inferred from electronic annotation. Source: UniProtKB-KW quinone binding Inferred from electronic annotation. Source: UniProtKB-KW
Complete GO annotation...

Sequence annotation (Features)

Feature key

Position(s)

Length

Description

Graphical view

Feature identifier

Molecule processing

Initiator methionine

1

1

Removed Ref.3

Chain

2 – 181

180

NADH-quinone oxidoreductase subunit 2

PRO_0000118686

Sites

Metal binding

83

1

Iron-sulfur (2Fe-2S)

Metal binding

88

1

Iron-sulfur (2Fe-2S)

Metal binding

124

1

Iron-sulfur (2Fe-2S)

Metal binding

128

1

Iron-sulfur (2Fe-2S)

Amino acid modifications

Disulfide bond

144 ↔ 172

Secondary structure

1

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181

Helix Strand Turn

Details...

Turn

4 – 7

4

Helix

8 – 16

9

Helix

23 – 26

4

Helix

27 – 38

12

Helix

43 – 53

11

Helix

57 – 66

10

Beta strand

67 – 70

4

Beta strand

77 – 83

7

Helix

86 – 89

4

Turn

90 – 92

3

Helix

93 – 104

12

Beta strand

117 – 123

7

Beta strand

130 – 132

3

Beta strand

137 – 141

5

Helix

147 – 158

12

Helix

163 – 165

3

Beta strand

174 – 176

3

Sequences

	Sequence		Length	Mass (Da)
	Q56221-1 [UniParc]. Last modified January 23, 2007. Version 3. Checksum: 484FE09245C613EE	FASTA	181	20,286
	10 20 30 40 50 60 MGFFDDKQDF LEETFAKYPP EGRRAAIMPL LRRVQQEEGW IRPERIEEIA RLVGTTPTEV 70 80 90 100 110 120 MGVASFYSYY QFVPTGKYHL QVCATLSCKL AGAEELWDYL TETLGIGPGE VTPDGLFSVQ 130 140 150 160 170 180 KVECLGSCHT APVIQVNDEP YVECVTRARL EALLAGLRAG KRLEEIELPG KCGHHVHEVE V

References

	« Hide 'large scale' referencesShow 'large scale' references »
[1]	"The proton-translocating NADH-quinone oxidoreductase (NDH-1) of thermophilic bacterium Thermus thermophilus HB-8. Complete DNA sequence of the gene cluster and thermostable properties of the expressed NQO2 subunit." Yano T., Chu S.S., Sled' V.D., Ohnishi T., Yagi T. J. Biol. Chem. 272:4201-4211(1997) [PubMed: 9020134] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA], CHARACTERIZATION.
[2]	"Complete genome sequence of Thermus thermophilus HB8." Masui R., Kurokawa K., Nakagawa N., Tokunaga F., Koyama Y., Shibata T., Oshima T., Yokoyama S., Yasunaga T., Kuramitsu S. Submitted (NOV-2004) to the EMBL/GenBank/DDBJ databases Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
[3]	"Identification of a novel subunit of respiratory complex I from Thermus thermophilus." Hinchliffe P., Carroll J., Sazanov L.A. Biochemistry 45:4413-4420(2006) [PubMed: 16584177] [Abstract] Cited for: PROTEIN SEQUENCE OF 2-9, IDENTIFICATION BY MASS SPECTROMETRY, EPR SPECTROSCOPY, SUBUNIT.
[4]	"Structure of the hydrophilic domain of respiratory complex I from Thermus thermophilus." Sazanov L.A., Hinchliffe P. Science 311:1430-1436(2006) [PubMed: 16469879] [Abstract] Cited for: X-RAY CRYSTALLOGRAPHY (3.3 ANGSTROMS), SUBUNIT, ELECTRON TRANSFER MECHANISM.
+	Additional computationally mapped references.

Cross-references

Sequence databases

EMBL
GenBank
DDBJ

U52917 Genomic DNA. Translation: AAA97942.1.
AP008226 Genomic DNA. Translation: BAD69911.1.

PIR

T11902.

RefSeq

YP_143354.1.

3D structure databases

PDBe
RCSB PDB
PDBj

Entry	Method	Resolution (Å)	Chain	Positions	PDBsum
2FUG	X-ray	3.30	2/B/K/T	1-181	[»]
3I9V	X-ray	3.10	2/B	1-181	[»]
3IAM	X-ray	3.10	2/B	1-181	[»]
3IAS	X-ray	3.15	2/B/K/T	1-181	[»]

ModBase

Search...

Protein-protein interaction databases

STRING

Q56221.

Protein family/group databases

TCDB

3.D.1.3.1. H+ or Na+-translocating NADH dehydrogenase (NDH) family.

Genome annotation databases

GeneID

3168326.

GenomeReviews

Gene locus TTHA0088 in contig AP008226_GR.

KEGG

ttj:TTHA0088.

Organism-specific databases

CMR

Search...

Phylogenomic databases

eggNOG

COG1905.

HOGENOM

HBG616790.

OMA

CRTTPCW.

Enzyme and pathway databases

BioCyc

TTHE300852:TTHA0088-MONOMER.

Family and domain databases

InterPro

IPR002023. NADH_UbQ_OxRdtase_24kDa_su.
IPR012336. Thioredoxin-like_fold.
IPR012335. Thioredoxin_fold.
[Graphical view]

Gene3D

G3DSA:3.40.30.10. Thioredoxin_fold. 1 hit.

PANTHER

PTHR10371. Cmplx1_24kDa. 1 hit.

Pfam

PF01257. Complex1_24kDa. 1 hit.
[Graphical view]

PIRSF

PIRSF000216. NADH_DH_24kDa. 1 hit.

TIGRFAMs

TIGR01958. nuoE_fam. 1 hit.

PROSITE

PS01099. COMPLEX1_24K. 1 hit.
[Graphical view]

ProtoNet

Search...

Entry information

Entry name

NQO2_THET8

Accession

Primary (citable) accession number: Q56221
Secondary accession number(s): Q5SM55

Entry history

Integrated into UniProtKB/Swiss-Prot:	November 1, 1997
Last sequence update:	January 23, 2007
Last modified:	February 9, 2010
This is version 76 of the entry and version 3 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation project

HAMAP (High-quality Automated and Manual Annotation of microbial Proteomes)