P51900 (HGXR_TRIFO) Reviewed, UniProtKB/Swiss-Prot

Names and origin

Protein names

Recommended name:
Hypoxanthine-guanine-xanthine phosphoribosyltransferase
Short name=HGPRT
Short name=HGXPRT
Short name=HGXPRTase
EC=2.4.2.-

Gene names

Name:

HPT

Organism

Tritrichomonas foetus (Trichomonas foetus) (Tritrichomonas suis)

Taxonomic identifier

56690 [NCBI]

Taxonomic lineage

Eukaryota › Parabasalia › Tritrichomonadida › Tritrichomonadidae › Tritrichomonas

Protein attributes

Sequence length	183 AA.
Sequence status	Complete.
Protein existence	Evidence at protein level

General annotation (Comments)

Function	Essential in nucleic acid metabolism of T.foetus because the parasite is unable to synthesize purine nucleotides de novo and relies on the HGXPRTase activities for its purine requirements by salvaging purine bases from the host. Works with guanine, hypoxanthine and xanthine.
Catalytic activity	IMP + diphosphate = hypoxanthine + 5-phospho-alpha-D-ribose 1-diphosphate. GMP + diphosphate = guanine + 5-phospho-alpha-D-ribose 1-diphosphate. 5-phospho-alpha-D-ribose 1-diphosphate + xanthine = (9-D-ribosylxanthine)-5'-phosphate + phosphate.
Cofactor	Binds 2 magnesium ions per subunit. The magnesium ions are essentially bound to the substrate and have few direct interactions with the protein By similarity.
Pathway	Purine metabolism; GMP biosynthesis via salvage pathway; GMP from guanine: step 1/1. Purine metabolism; IMP biosynthesis via salvage pathway; IMP from hypoxanthine: step 1/1. Purine metabolism; XMP biosynthesis via salvage pathway; XMP from xanthine: step 1/1.
Subunit structure	Homodimer.
Subcellular location	Cytoplasm.
Sequence similarities	Belongs to the purine/pyrimidine phosphoribosyltransferase family.
Mass spectrometry	Molecular mass is 21091.04±1.48 Da from positions 1 - 183. Determined by ESI. Ref.2

Ontologies

Keywords
Biological process	Purine salvage
Cellular component	Cytoplasm
Ligand	Magnesium Metal-binding Nucleotide-binding
Molecular function	Glycosyltransferase Transferase
Technical term	3D-structure
Gene Ontology (GO)
Biological process	purine ribonucleoside salvage Inferred from electronic annotation. Source: UniProtKB-KW
Cellular component	cytoplasm Inferred from electronic annotation. Source: UniProtKB-SubCell
Molecular function	hypoxanthine phosphoribosyltransferase activity Inferred from electronic annotation. Source: InterPro metal ion binding Inferred from electronic annotation. Source: UniProtKB-KW nucleotide 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

Chain

1 – 183

183

Hypoxanthine-guanine-xanthine phosphoribosyltransferase

PRO_0000139600

Regions

Nucleotide binding

102 – 110

9

GMP

Sites

Active site

106

1

Proton acceptor By similarity

Metal binding

163

1

Magnesium By similarity

Binding site

134

1

GMP

Binding site

163

1

GMP; via carbonyl oxygen

Secondary structure

1

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183

Helix Strand Turn

Details...

Beta strand

10 – 15

6

Helix

17 – 35

19

Turn

36 – 38

3

Beta strand

41 – 45

5

Turn

46 – 49

4

Helix

50 – 57

8

Beta strand

65 – 72

8

Beta strand

84 – 87

4

Beta strand

96 – 108

13

Helix

109 – 119

11

Beta strand

124 – 134

11

Beta strand

146 – 152

7

Beta strand

157 – 159

3

Beta strand

172 – 177

6

Sequences

	Sequence		Length	Mass (Da)
	P51900 [UniParc]. Last modified October 1, 1996. Version 1. Checksum: A151E2F5D7D1C214	FASTA	183	21,091
	10 20 30 40 50 60 MTETPMMDDL ERVLYNQDDI QKRIRELAAE LTEFYEDKNP VMICVLTGAV FFYTDLLKHL 70 80 90 100 110 120 DFQLEPDYII CSSYSGTKST GNLTISKDLK TNIEGRHVLV VEDIIDTGLT MYQLLNNLQM 130 140 150 160 170 180 RKPASLKVCT LCDKDIGKKA YDVPIDYCGF VVENRYIIGY GFDFHNKYRN LPVIGILKES VYT

References

[1]	"Isolation, sequencing and expression of the gene encoding hypoxanthine-guanine-xanthine phosphoribosyltransferase of Tritrichomonas foetus." Chin M.S., Wang C.C. Mol. Biochem. Parasitol. 63:221-229(1994) [PubMed: 8008020] [Abstract] Cited for: NUCLEOTIDE SEQUENCE. Strain: KV1.
[2]	"Crystal structure of the hypoxanthine-guanine-xanthine phosphoribosyltransferase from the protozoan parasite Tritrichomonas foetus." Somoza J.R., Chin M.S., Focia P.J., Wang C.C., Fletterick R.J. Biochemistry 35:7032-7040(1996) [PubMed: 8679528] [Abstract] Cited for: X-RAY CRYSTALLOGRAPHY (1.9 ANGSTROMS), MASS SPECTROMETRY.
[3]	"Probing the active site of Tritrichomonas foetus hypoxanthine-guanine-xanthine phosphoribosyltransferase using covalent modification of cysteine residues." Kanaani J., Somoza J.R., Maltby D., Wang C.C. Eur. J. Biochem. 239:764-772(1996) [PubMed: 8774725] [Abstract] Cited for: COVALENT MODIFICATION OF CYSTEINES.
+	Additional computationally mapped references.

Cross-references

Sequence databases

EMBL
GenBank
DDBJ

L08622 Unassigned DNA. Translation: AAC37202.1.

3D structure databases

PDBe
RCSB PDB
PDBj

Entry	Method	Resolution (Å)	Chain	Positions	PDBsum
1HGX	X-ray	1.90	A/B	1-183	[»]

ProteinModelPortal

P51900.

SMR

P51900. Positions 7-179.

ModBase

Search...

Protocols and materials databases

StructuralBiologyKnowledgebase

Search...

Family and domain databases

InterPro

IPR005904. Hxn_phspho_trans.
IPR000836. PRibTrfase.
[Graphical view]

Pfam

PF00156. Pribosyltran. 1 hit.
[Graphical view]

TIGRFAMs

TIGR01203. HGPRTase. 1 hit.

PROSITE

PS00103. PUR_PYR_PR_TRANSFER. 1 hit.
[Graphical view]

ProtoNet

Search...

Entry information

Entry name

HGXR_TRIFO

Accession

Primary (citable) accession number: P51900

Entry history

Integrated into UniProtKB/Swiss-Prot:	October 1, 1996
Last sequence update:	October 1, 1996
Last modified:	September 21, 2011
This is version 70 of the entry and version 1 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)