(data stored in SCRATCH zone)

SWISSPROT: IUNH_CRIFA

ID   IUNH_CRIFA              Reviewed;         315 AA.
AC   Q27546;
DT   01-NOV-1997, integrated into UniProtKB/Swiss-Prot.
DT   23-JAN-2007, sequence version 3.
DT   11-DEC-2019, entry version 92.
DE   RecName: Full=Inosine-uridine preferring nucleoside hydrolase {ECO:0000303|PubMed:8634238};
DE            Short=IU-NH {ECO:0000303|PubMed:8634238};
DE            Short=IU-nucleoside hydrolase {ECO:0000303|PubMed:8634238};
DE            EC=3.2.2.2 {ECO:0000269|PubMed:1939115};
DE            EC=3.2.2.3 {ECO:0000269|PubMed:1939115};
DE   AltName: Full=Non-specific nucleoside hydrolase {ECO:0000303|PubMed:1939115};
GN   Name=IUNH;
OS   Crithidia fasciculata.
OC   Eukaryota; Euglenozoa; Kinetoplastida; Trypanosomatidae; Leishmaniinae;
OC   Crithidia.
OX   NCBI_TaxID=5656;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA], PARTIAL PROTEIN SEQUENCE, MASS
RP   SPECTROMETRY, AND MUTAGENESIS.
RX   PubMed=8634237; DOI=10.1021/bi952998u;
RA   Gopaul D.N., Meyer S.L., Degano M., Sacchettini J.C., Schramm V.L.;
RT   "Inosine-uridine nucleoside hydrolase from Crithidia fasciculata. Genetic
RT   characterization, crystallization, and identification of histidine 241 as a
RT   catalytic site residue.";
RL   Biochemistry 35:5963-5970(1996).
RN   [2]
RP   FUNCTION, CATALYTIC ACTIVITY, SUBSTRATE SPECIFICITY, BIOPHYSICOCHEMICAL
RP   PROPERTIES, SUBUNIT, AND PATHWAY.
RX   PubMed=1939115;
RA   Parkin D.W., Horenstein B.A., Abdulah D.R., Estupinan B., Schramm V.L.;
RT   "Nucleoside hydrolase from Crithidia fasciculata. Metabolic role,
RT   purification, specificity, and kinetic mechanism.";
RL   J. Biol. Chem. 266:20658-20665(1991).
RN   [3]
RP   X-RAY CRYSTALLOGRAPHY (2.5 ANGSTROMS) IN COMPLEX WITH SUBSTRATE AND CALCIUM
RP   IONS, AND ACTIVE SITE.
RX   PubMed=8634238; DOI=10.1021/bi952999m;
RA   Degano M., Gopaul D.N., Scapin G., Schramm V.L., Sacchettini J.C.;
RT   "Three-dimensional structure of the inosine-uridine nucleoside N-
RT   ribohydrolase from Crithidia fasciculata.";
RL   Biochemistry 35:5971-5981(1996).
CC   -!- FUNCTION: Catalyzes the hydrolysis of the N-glycosidic bond of commonly
CC       occurring purine and pyrimidine nucleosides into ribose and the base,
CC       but has a preference for inosine and uridine as substrates. Is not
CC       active on thymidine and 2'-deoxynucleosides. Functions in purine
CC       salvage from the blood of the host, a fundamental pathway since
CC       protozoan parasites such as C.fasciculata are incapable of de novo
CC       purine biosynthesis. {ECO:0000269|PubMed:1939115}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=H2O + inosine = D-ribose + hypoxanthine; Xref=Rhea:RHEA:16657,
CC         ChEBI:CHEBI:15377, ChEBI:CHEBI:17368, ChEBI:CHEBI:17596,
CC         ChEBI:CHEBI:47013; EC=3.2.2.2; Evidence={ECO:0000269|PubMed:1939115};
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=H2O + uridine = D-ribose + uracil; Xref=Rhea:RHEA:15577,
CC         ChEBI:CHEBI:15377, ChEBI:CHEBI:16704, ChEBI:CHEBI:17568,
CC         ChEBI:CHEBI:47013; EC=3.2.2.3; Evidence={ECO:0000269|PubMed:1939115};
CC   -!- COFACTOR:
CC       Name=Ca(2+); Xref=ChEBI:CHEBI:29108;
CC         Evidence={ECO:0000250|UniProtKB:P83851};
CC   -!- BIOPHYSICOCHEMICAL PROPERTIES:
CC       Kinetic parameters:
CC         KM=380 uM for inosine {ECO:0000269|PubMed:1939115};
CC         KM=460 uM for adenosine {ECO:0000269|PubMed:1939115};
CC         KM=420 uM for guanosine {ECO:0000269|PubMed:1939115};
CC         KM=145 uM for purine riboside {ECO:0000269|PubMed:1939115};
CC         KM=1300 uM for 5-methyluridine {ECO:0000269|PubMed:1939115};
CC         KM=1220 uM for uridine {ECO:0000269|PubMed:1939115};
CC         KM=4700 uM for cytosine {ECO:0000269|PubMed:1939115};
CC         Vmax=50 umol/min/mg enzyme with inosine as substrate
CC         {ECO:0000269|PubMed:1939115};
CC         Vmax=7.6 umol/min/mg enzyme with adenosine as substrate
CC         {ECO:0000269|PubMed:1939115};
CC         Vmax=70 umol/min/mg enzyme with guanosine as substrate
CC         {ECO:0000269|PubMed:1939115};
CC         Vmax=0.03 umol/min/mg enzyme with purine riboside as substrate
CC         {ECO:0000269|PubMed:1939115};
CC         Vmax=380 umol/min/mg enzyme with 5-methyluridine as substrate
CC         {ECO:0000269|PubMed:1939115};
CC         Vmax=255 umol/min/mg enzyme with uridine as substrate
CC         {ECO:0000269|PubMed:1939115};
CC         Vmax=36 umol/min/mg enzyme with cytosine as substrate
CC         {ECO:0000269|PubMed:1939115};
CC         Note=kcat is 32 sec(-1) with inosine as substrate. kcat is 243 sec(-
CC         1) with 5-methyluridine as substrate. {ECO:0000269|PubMed:1939115};
CC   -!- PATHWAY: Purine metabolism; purine nucleoside salvage.
CC       {ECO:0000305|PubMed:1939115}.
CC   -!- SUBUNIT: Homotetramer. {ECO:0000269|PubMed:1939115}.
CC   -!- MASS SPECTROMETRY: Mass=34194; Mass_error=4; Method=Electrospray;
CC       Evidence={ECO:0000269|PubMed:8634237};
CC   -!- SIMILARITY: Belongs to the IUNH family. {ECO:0000305}.
DR   EMBL; U43371; AAC47119.1; -; Genomic_DNA.
DR   PDB; 1MAS; X-ray; 2.50 A; A/B=3-315.
DR   PDB; 2MAS; X-ray; 2.30 A; A/B/C/D=3-315.
DR   PDBsum; 1MAS; -.
DR   PDBsum; 2MAS; -.
DR   SMR; Q27546; -.
DR   BindingDB; Q27546; -.
DR   ChEMBL; CHEMBL3826862; -.
DR   BRENDA; 3.2.2.3; 1365.
DR   UniPathway; UPA00606; -.
DR   EvolutionaryTrace; Q27546; -.
DR   GO; GO:0047724; F:inosine nucleosidase activity; IEA:UniProtKB-EC.
DR   GO; GO:0046872; F:metal ion binding; IEA:UniProtKB-KW.
DR   GO; GO:0045437; F:uridine nucleosidase activity; IEA:UniProtKB-EC.
DR   GO; GO:0009117; P:nucleotide metabolic process; IEA:UniProtKB-KW.
DR   Gene3D; 3.90.245.10; -; 1.
DR   InterPro; IPR015910; I/U_nuclsd_hydro_CS.
DR   InterPro; IPR001910; Inosine/uridine_hydrolase_dom.
DR   InterPro; IPR023186; IUNH.
DR   InterPro; IPR036452; Ribo_hydro-like.
DR   PANTHER; PTHR12304; PTHR12304; 1.
DR   Pfam; PF01156; IU_nuc_hydro; 1.
DR   SUPFAM; SSF53590; SSF53590; 1.
DR   PROSITE; PS01247; IUNH; 1.
PE   1: Evidence at protein level;
DR   PRODOM; Q27546.
DR   SWISS-2DPAGE; Q27546.
KW   3D-structure; Calcium; Direct protein sequencing; Glycosidase; Hydrolase;
KW   Metal-binding; Nucleotide metabolism.
FT   INIT_MET        1
FT                   /note="Removed"
FT   CHAIN           2..315
FT                   /note="Inosine-uridine preferring nucleoside hydrolase"
FT                   /id="PRO_0000206810"
FT   ACT_SITE        241
FT                   /note="Proton donor"
FT                   /evidence="ECO:0000305|PubMed:8634238"
FT   METAL           10
FT                   /note="Calcium"
FT   METAL           15
FT                   /note="Calcium"
FT   METAL           126
FT                   /note="Calcium"
FT   METAL           242
FT                   /note="Calcium"
FT   BINDING         14
FT                   /note="Substrate"
FT                   /evidence="ECO:0000269|PubMed:8634238"
FT   BINDING         160
FT                   /note="Substrate"
FT                   /evidence="ECO:0000269|PubMed:8634238"
FT   BINDING         166
FT                   /note="Substrate"
FT                   /evidence="ECO:0000269|PubMed:8634238"
FT   BINDING         168
FT                   /note="Substrate"
FT                   /evidence="ECO:0000269|PubMed:8634238"
FT   MUTAGEN         241
FT                   /note="H->A: Loss of activity."
FT                   /evidence="ECO:0000269|PubMed:8634237"
FT   STRAND          3..9
FT                   /evidence="ECO:0000244|PDB:2MAS"
FT   HELIX           13..24
FT                   /evidence="ECO:0000244|PDB:2MAS"
FT   STRAND          28..35
FT                   /evidence="ECO:0000244|PDB:2MAS"
FT   STRAND          37..40
FT                   /evidence="ECO:0000244|PDB:2MAS"
FT   HELIX           42..55
FT                   /evidence="ECO:0000244|PDB:2MAS"
FT   STRAND          63..65
FT                   /evidence="ECO:0000244|PDB:2MAS"
FT   STRAND          71..73
FT                   /evidence="ECO:0000244|PDB:2MAS"
FT   HELIX           79..82
FT                   /evidence="ECO:0000244|PDB:2MAS"
FT   STRAND          84..87
FT                   /evidence="ECO:0000244|PDB:2MAS"
FT   HELIX           105..115
FT                   /evidence="ECO:0000244|PDB:2MAS"
FT   STRAND          121..125
FT                   /evidence="ECO:0000244|PDB:2MAS"
FT   HELIX           130..138
FT                   /evidence="ECO:0000244|PDB:2MAS"
FT   HELIX           142..145
FT                   /evidence="ECO:0000244|PDB:2MAS"
FT   STRAND          148..152
FT                   /evidence="ECO:0000244|PDB:2MAS"
FT   STRAND          160..164
FT                   /evidence="ECO:0000244|PDB:2MAS"
FT   HELIX           167..170
FT                   /evidence="ECO:0000244|PDB:2MAS"
FT   HELIX           173..181
FT                   /evidence="ECO:0000244|PDB:2MAS"
FT   STRAND          182..184
FT                   /evidence="ECO:0000244|PDB:2MAS"
FT   STRAND          186..189
FT                   /evidence="ECO:0000244|PDB:2MAS"
FT   HELIX           191..194
FT                   /evidence="ECO:0000244|PDB:2MAS"
FT   HELIX           201..208
FT                   /evidence="ECO:0000244|PDB:2MAS"
FT   HELIX           213..230
FT                   /evidence="ECO:0000244|PDB:2MAS"
FT   STRAND          236..239
FT                   /evidence="ECO:0000244|PDB:2MAS"
FT   HELIX           242..250
FT                   /evidence="ECO:0000244|PDB:2MAS"
FT   HELIX           252..254
FT                   /evidence="ECO:0000244|PDB:2MAS"
FT   STRAND          255..259
FT                   /evidence="ECO:0000244|PDB:2MAS"
FT   STRAND          262..264
FT                   /evidence="ECO:0000244|PDB:2MAS"
FT   TURN            269..273
FT                   /evidence="ECO:0000244|PDB:1MAS"
FT   STRAND          275..277
FT                   /evidence="ECO:0000244|PDB:2MAS"
FT   STRAND          288..295
FT                   /evidence="ECO:0000244|PDB:2MAS"
FT   HELIX           297..311
FT                   /evidence="ECO:0000244|PDB:2MAS"
SQ   SEQUENCE   315 AA;  34326 MW;  B88CF9DA41B53F43 CRC64;
     MPKKIILDCD PGLDDAVAIL LAHGNPEIEL LAITTVVGNQ TLAKVTRNAQ LVADIAGITG
     VPIAAGCDKP LVRKIMTAGH IHGESGMGTV AYPAEFKNKV DERHAVNLII DLVMSHEPKT
     ITLVPTGGLT NIAMAARLEP RIVDRVKEVV LMGGGYHEGN ATSVAEFNII IDPEAAHIVF
     NESWQVTMVG LDLTHQALAT PPILQRVKEV DTNPARFMLE IMDYYTKIYQ SNRYMAAAAV
     HDPCAVAYVI DPSVMTTERV PVDIELTGKL TLGMTVADFR NPRPEHCHTQ VAVKLDFEKF
     WGLVLDALER IGDPQ
//

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