ID   MTNN_ERWT9              Reviewed;         232 AA.
AC   B2VE28;
DT   20-JAN-2009, integrated into UniProtKB/Swiss-Prot.
DT   01-JUL-2008, sequence version 1.
DT   04-NOV-2026, entry version 91.
DE   RecName: Full=5'-methylthioadenosine/S-adenosylhomocysteine nucleosidase {ECO:0000255|HAMAP-Rule:MF_01684};
DE            Short=MTA/SAH nucleosidase {ECO:0000255|HAMAP-Rule:MF_01684};
DE            Short=MTAN {ECO:0000255|HAMAP-Rule:MF_01684};
DE            EC=3.2.2.9 {ECO:0000255|HAMAP-Rule:MF_01684};
DE   AltName: Full=5'-deoxyadenosine nucleosidase {ECO:0000255|HAMAP-Rule:MF_01684};
DE            Short=DOA nucleosidase {ECO:0000255|HAMAP-Rule:MF_01684};
DE            Short=dAdo nucleosidase {ECO:0000255|HAMAP-Rule:MF_01684};
DE   AltName: Full=5'-methylthioadenosine nucleosidase {ECO:0000255|HAMAP-Rule:MF_01684};
DE            Short=MTA nucleosidase {ECO:0000255|HAMAP-Rule:MF_01684};
DE   AltName: Full=S-adenosylhomocysteine nucleosidase {ECO:0000255|HAMAP-Rule:MF_01684};
DE            Short=AdoHcy nucleosidase {ECO:0000255|HAMAP-Rule:MF_01684};
DE            Short=SAH nucleosidase {ECO:0000255|HAMAP-Rule:MF_01684};
DE            Short=SRH nucleosidase {ECO:0000255|HAMAP-Rule:MF_01684};
GN   Name=mtnN {ECO:0000255|HAMAP-Rule:MF_01684};
GN   OrderedLocusNames=ETA_08820;
OS   Erwinia tasmaniensis (strain DSM 17950 / CFBP 7177 / CIP 109463 / NCPPB
OS   4357 / Et1/99).
OC   Bacteria; Pseudomonadati; Pseudomonadota; Gammaproteobacteria;
OC   Enterobacterales; Erwiniaceae; Erwinia.
OX   NCBI_TaxID=465817;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=DSM 17950 / CFBP 7177 / CIP 109463 / NCPPB 4357 / Et1/99;
RX   PubMed=18462403; DOI=10.1111/j.1462-2920.2008.01639.x;
RA   Kube M., Migdoll A.M., Mueller I., Kuhl H., Beck A., Reinhardt R.,
RA   Geider K.;
RT   "The genome of Erwinia tasmaniensis strain Et1/99, a non-pathogenic
RT   bacterium in the genus Erwinia.";
RL   Environ. Microbiol. 10:2211-2222(2008).
CC   -!- FUNCTION: Catalyzes the irreversible cleavage of the glycosidic bond in
CC       both 5'-methylthioadenosine (MTA) and S-adenosylhomocysteine
CC       (SAH/AdoHcy) to adenine and the corresponding thioribose, 5'-
CC       methylthioribose and S-ribosylhomocysteine, respectively. Also cleaves
CC       5'-deoxyadenosine, a toxic by-product of radical S-adenosylmethionine
CC       (SAM) enzymes, into 5-deoxyribose and adenine. Thus, is required for in
CC       vivo function of the radical SAM enzymes biotin synthase and lipoic
CC       acid synthase, that are inhibited by 5'-deoxyadenosine accumulation.
CC       {ECO:0000255|HAMAP-Rule:MF_01684}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=S-adenosyl-L-homocysteine + H2O = S-(5-deoxy-D-ribos-5-yl)-L-
CC         homocysteine + adenine; Xref=Rhea:RHEA:17805, ChEBI:CHEBI:15377,
CC         ChEBI:CHEBI:16708, ChEBI:CHEBI:57856, ChEBI:CHEBI:58195; EC=3.2.2.9;
CC         Evidence={ECO:0000255|HAMAP-Rule:MF_01684};
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=S-methyl-5'-thioadenosine + H2O = 5-(methylsulfanyl)-D-ribose
CC         + adenine; Xref=Rhea:RHEA:13617, ChEBI:CHEBI:15377,
CC         ChEBI:CHEBI:16708, ChEBI:CHEBI:17509, ChEBI:CHEBI:78440; EC=3.2.2.9;
CC         Evidence={ECO:0000255|HAMAP-Rule:MF_01684};
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=5'-deoxyadenosine + H2O = 5-deoxy-D-ribose + adenine;
CC         Xref=Rhea:RHEA:29859, ChEBI:CHEBI:15377, ChEBI:CHEBI:16708,
CC         ChEBI:CHEBI:17319, ChEBI:CHEBI:149540; EC=3.2.2.9;
CC         Evidence={ECO:0000255|HAMAP-Rule:MF_01684};
CC       PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:29860;
CC         Evidence={ECO:0000255|HAMAP-Rule:MF_01684};
CC   -!- PATHWAY: Amino-acid biosynthesis; L-methionine biosynthesis via salvage
CC       pathway; S-methyl-5-thio-alpha-D-ribose 1-phosphate from S-methyl-5'-
CC       thioadenosine (hydrolase route): step 1/2. {ECO:0000255|HAMAP-
CC       Rule:MF_01684}.
CC   -!- SUBUNIT: Homodimer. {ECO:0000255|HAMAP-Rule:MF_01684}.
CC   -!- SIMILARITY: Belongs to the PNP/UDP phosphorylase family. MtnN
CC       subfamily. {ECO:0000255|HAMAP-Rule:MF_01684}.
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DR   EMBL; CU468135; CAO95928.1; -; Genomic_DNA.
DR   RefSeq; WP_012440630.1; NC_010694.1.
DR   AlphaFoldDB; B2VE28; -.
DR   SMR; B2VE28; -.
DR   STRING; 465817.ETA_08820; -.
DR   KEGG; eta:ETA_08820; -.
DR   eggNOG; COG0775; Bacteria.
DR   HOGENOM; CLU_031248_2_2_6; -.
DR   OMA; AAFCMNT; -.
DR   OrthoDB; 9792278at2; -.
DR   UniPathway; UPA00904; UER00871.
DR   Proteomes; UP000001726; Chromosome.
DR   GO; GO:0005829; C:cytosol; IEA:TreeGrafter.
DR   GO; GO:0008782; F:adenosylhomocysteine nucleosidase activity; IEA:UniProtKB-UniRule.
DR   GO; GO:0008930; F:methylthioadenosine nucleosidase activity; IEA:UniProtKB-UniRule.
DR   GO; GO:0033353; P:L-methionine cycle; IEA:InterPro.
DR   GO; GO:0046124; P:purine deoxyribonucleoside catabolic process; IEA:UniProtKB-UniRule.
DR   CDD; cd09008; MTAN; 1.
DR   FunFam; 3.40.50.1580:FF:000001; MTA/SAH nucleosidase family protein; 1.
DR   Gene3D; 3.40.50.1580; Nucleoside phosphorylase domain; 1.
DR   HAMAP; MF_01684; Salvage_MtnN; 1.
DR   InterPro; IPR010049; MTA_SAH_Nsdase.
DR   InterPro; IPR000845; Nucleoside_phosphorylase_d.
DR   InterPro; IPR035994; Nucleoside_phosphorylase_sf.
DR   NCBIfam; TIGR01704; MTA_SAH-Nsdase; 1.
DR   NCBIfam; NF004079; PRK05584.1; 1.
DR   PANTHER; PTHR46832; 5'-METHYLTHIOADENOSINE/S-ADENOSYLHOMOCYSTEINE NUCLEOSIDASE; 1.
DR   PANTHER; PTHR46832:SF1; 5'-METHYLTHIOADENOSINE_S-ADENOSYLHOMOCYSTEINE NUCLEOSIDASE; 1.
DR   Pfam; PF01048; PNP_UDP_1; 1.
DR   SUPFAM; SSF53167; Purine and uridine phosphorylases; 1.
PE   3: Inferred from homology;
KW   Amino-acid biosynthesis; Hydrolase; Methionine biosynthesis;
KW   Reference proteome.
FT   CHAIN           1..232
FT                   /note="5'-methylthioadenosine/S-adenosylhomocysteine
FT                   nucleosidase"
FT                   /id="PRO_0000359292"
FT   ACT_SITE        12
FT                   /note="Proton acceptor"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01684"
FT   ACT_SITE        197
FT                   /note="Proton donor"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01684"
FT   BINDING         78
FT                   /ligand="substrate"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01684"
FT   BINDING         152
FT                   /ligand="substrate"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01684"
FT   BINDING         173..174
FT                   /ligand="substrate"
FT                   /evidence="ECO:0000255|HAMAP-Rule:MF_01684"
SQ   SEQUENCE   232 AA;  24318 MW;  7D603CAA7C77EB86 CRC64;
     MKAGIIGAME QEVTLLRDKI ENRQTLTLAG CEIYTGTLNG VDVALLKSGI GKVSAALGTT
     LLLELCKPDV VINTGSAGGL AATLKVGDIV VSDEVRYHDA DVTAFGYEAG QMAGCPAAFK
     ADEKLITAVE QCIHQLDLHA VRGLVVSGDA FINGAAPLAH IRNTFPQAIA VEMEATAIGH
     VCHQFGTPFV VVRAISDVAD QQSHLSFDEF LAVAAKQSSL LVEKLLAHLA QG
//