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 03-AUG-2022, entry version 98.
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; Discoba; Euglenozoa; Kinetoplastea; Metakinetoplastina;
OC Trypanosomatida; Trypanosomatidae; Leishmaniinae; 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; DOI=10.1016/s0021-9258(18)54759-1;
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}.
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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 AlphaFoldDB; Q27546; -.
DR SMR; Q27546; -.
DR BindingDB; Q27546; -.
DR ChEMBL; CHEMBL3826862; -.
DR KEGG; ag:AAC47119; -.
DR VEuPathDB; TriTrypDB:CFAC1_140027700; -.
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 GO; GO:1901564; P:organonitrogen compound metabolic process; IEA:UniProt.
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;
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 BINDING 10
FT /ligand="Ca(2+)"
FT /ligand_id="ChEBI:CHEBI:29108"
FT BINDING 14
FT /ligand="substrate"
FT /evidence="ECO:0000269|PubMed:8634238"
FT BINDING 15
FT /ligand="Ca(2+)"
FT /ligand_id="ChEBI:CHEBI:29108"
FT BINDING 126
FT /ligand="Ca(2+)"
FT /ligand_id="ChEBI:CHEBI:29108"
FT BINDING 160
FT /ligand="substrate"
FT /evidence="ECO:0000269|PubMed:8634238"
FT BINDING 166
FT /ligand="substrate"
FT /evidence="ECO:0000269|PubMed:8634238"
FT BINDING 168
FT /ligand="substrate"
FT /evidence="ECO:0000269|PubMed:8634238"
FT BINDING 242
FT /ligand="Ca(2+)"
FT /ligand_id="ChEBI:CHEBI:29108"
FT MUTAGEN 241
FT /note="H->A: Loss of activity."
FT /evidence="ECO:0000269|PubMed:8634237"
FT STRAND 3..9
FT /evidence="ECO:0007829|PDB:2MAS"
FT HELIX 13..24
FT /evidence="ECO:0007829|PDB:2MAS"
FT STRAND 28..35
FT /evidence="ECO:0007829|PDB:2MAS"
FT STRAND 37..40
FT /evidence="ECO:0007829|PDB:2MAS"
FT HELIX 42..55
FT /evidence="ECO:0007829|PDB:2MAS"
FT STRAND 63..65
FT /evidence="ECO:0007829|PDB:2MAS"
FT STRAND 71..73
FT /evidence="ECO:0007829|PDB:2MAS"
FT HELIX 79..82
FT /evidence="ECO:0007829|PDB:2MAS"
FT STRAND 84..87
FT /evidence="ECO:0007829|PDB:2MAS"
FT HELIX 105..115
FT /evidence="ECO:0007829|PDB:2MAS"
FT STRAND 121..125
FT /evidence="ECO:0007829|PDB:2MAS"
FT HELIX 130..138
FT /evidence="ECO:0007829|PDB:2MAS"
FT HELIX 142..145
FT /evidence="ECO:0007829|PDB:2MAS"
FT STRAND 148..152
FT /evidence="ECO:0007829|PDB:2MAS"
FT STRAND 160..164
FT /evidence="ECO:0007829|PDB:2MAS"
FT HELIX 167..170
FT /evidence="ECO:0007829|PDB:2MAS"
FT HELIX 173..181
FT /evidence="ECO:0007829|PDB:2MAS"
FT STRAND 182..184
FT /evidence="ECO:0007829|PDB:2MAS"
FT STRAND 186..189
FT /evidence="ECO:0007829|PDB:2MAS"
FT HELIX 191..194
FT /evidence="ECO:0007829|PDB:2MAS"
FT HELIX 201..208
FT /evidence="ECO:0007829|PDB:2MAS"
FT HELIX 213..230
FT /evidence="ECO:0007829|PDB:2MAS"
FT STRAND 236..239
FT /evidence="ECO:0007829|PDB:2MAS"
FT HELIX 242..250
FT /evidence="ECO:0007829|PDB:2MAS"
FT HELIX 252..254
FT /evidence="ECO:0007829|PDB:2MAS"
FT STRAND 255..259
FT /evidence="ECO:0007829|PDB:2MAS"
FT STRAND 262..264
FT /evidence="ECO:0007829|PDB:2MAS"
FT TURN 269..273
FT /evidence="ECO:0007829|PDB:1MAS"
FT STRAND 275..277
FT /evidence="ECO:0007829|PDB:2MAS"
FT STRAND 288..295
FT /evidence="ECO:0007829|PDB:2MAS"
FT HELIX 297..311
FT /evidence="ECO:0007829|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
