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Protein

5'-methylthioadenosine/S-adenosylhomocysteine nucleosidase

Gene

mtnN

Organism
Escherichia coli (strain K12)
Status
Reviewed-Annotation score: -Experimental evidence at protein leveli

Functioni

Catalyzes the irreversible cleavage of the glycosidic bond in both 5'-methylthioadenosine (MTA) and S-adenosylhomocysteine (SAH/AdoHcy) to adenine and the corresponding thioribose, 5'-methylthioribose and S-ribosylhomocysteine, respectively. Can also use 5'-isobutylthioadenosine, 5'-n-butylthioadenosine, S-adenosyl-D-homocysteine, decarboxylated adenosylhomocysteine, deaminated adenosylhomocysteine and S-2-aza-adenosylhomocysteine as substrates.1 Publication

Catalytic activityi

S-adenosyl-L-homocysteine + H2O = S-(5-deoxy-D-ribos-5-yl)-L-homocysteine + adenine.1 Publication
S-methyl-5'-thioadenosine + H2O = S-methyl-5-thio-D-ribose + adenine.1 Publication

Enzyme regulationi

Strongly inhibited by aryl-substituted MTA analogs, alkyl-substituted MTA analogs, 5'-methylthioformycin, 5'-chloroformycin, S-formycinylhomocysteine, 5'-methylthiotubercidin, S-tubercidinylhomocysteine and S-8-aza-adenosylhomocysteine. Poorly inhibited by 5'-isobutylthioinosine, 5'-n-butylthioinosine, 5'-methylthio-3-deaza-adenosine, 5'-isobutylthio-3-deaza-adenosine, S-n-6-methyl-3-deaza-adenosylhomocysteine, S-adenosylhomocysteine sulphoxide and Sinefungin.4 Publications

Kineticsi

kcat is 3.0 sec(-1) and 2.6 sec(-1) with 5'-methylthioadenosine and S-adenosylhomocysteine as substrate, respectively.1 Publication
  1. KM=0.43 µM for 5'-methylthioadenosine (at pH 7 and 37 degrees Celsius)3 Publications
  2. KM=0.8 µM for 5'-methylthioadenosine (at pH 7 and 22 degrees Celsius)3 Publications
  3. KM=4.3 µM for S-adenosylhomocysteine (at pH 7 and 37 degrees Celsius)3 Publications
  4. KM=1.3 µM for S-adenosylhomocysteine (at pH 7 and 22 degrees Celsius)3 Publications
  1. Vmax=373 µmol/min/mg enzyme with 5'-methylthioadenosine as substrate (at pH 7 and 37 degrees Celsius)3 Publications
  2. Vmax=156 µmol/min/mg enzyme with S-adenosylhomocysteine as substrate (at pH 7 and 37 degrees Celsius)3 Publications

pH dependencei

Exhibits activity across a broad pH range. Enzyme activity is moderately improved under acidic conditions.2 Publications

Temperature dependencei

Optimum temperature is 37-45 degrees Celsius. Rapidly inactivated after exposure for 10 minutes at 55 degrees Celsius.2 Publications

Pathwayi: L-methionine biosynthesis via salvage pathway

This protein is involved in step 1 of the subpathway that synthesizes S-methyl-5-thio-alpha-D-ribose 1-phosphate from S-methyl-5'-thioadenosine (hydrolase route).
Proteins known to be involved in the 2 steps of the subpathway in this organism are:
  1. 5'-methylthioadenosine/S-adenosylhomocysteine nucleosidase (mtnN)
  2. no protein annotated in this organism
This subpathway is part of the pathway L-methionine biosynthesis via salvage pathway, which is itself part of Amino-acid biosynthesis.
View all proteins of this organism that are known to be involved in the subpathway that synthesizes S-methyl-5-thio-alpha-D-ribose 1-phosphate from S-methyl-5'-thioadenosine (hydrolase route), the pathway L-methionine biosynthesis via salvage pathway and in Amino-acid biosynthesis.

Sites

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Active sitei12Proton acceptor1 Publication1
Binding sitei78Substrate; via amide nitrogen1 Publication1
Binding sitei152Substrate; via amide nitrogen and carbonyl oxygen1 Publication1
Active sitei197Proton donor1 Publication1

GO - Molecular functioni

  • adenosylhomocysteine nucleosidase activity Source: EcoCyc
  • identical protein binding Source: IntAct
  • methylthioadenosine nucleosidase activity Source: EcoCyc

GO - Biological processi

Keywordsi

Molecular functionHydrolase
Biological processAmino-acid biosynthesis, Methionine biosynthesis

Enzyme and pathway databases

BioCyciEcoCyc:EG11090-MONOMER
MetaCyc:EG11090-MONOMER
BRENDAi3.2.2.30 2026
3.2.2.9 2026
UniPathwayiUPA00904; UER00871

Names & Taxonomyi

Protein namesi
Recommended name:
5'-methylthioadenosine/S-adenosylhomocysteine nucleosidase (EC:3.2.2.9)
Short name:
MTA/SAH nucleosidase
Short name:
MTAN
Alternative name(s):
5'-methylthioadenosine nucleosidase
Short name:
MTA nucleosidase
P46
S-adenosylhomocysteine nucleosidase
Short name:
AdoHcy nucleosidase
Short name:
SAH nucleosidase
Short name:
SRH nucleosidase
Gene namesi
Name:mtnN
Synonyms:mtn, pfs, yadA
Ordered Locus Names:b0159, JW0155
OrganismiEscherichia coli (strain K12)
Taxonomic identifieri83333 [NCBI]
Taxonomic lineageiBacteriaProteobacteriaGammaproteobacteriaEnterobacteralesEnterobacteriaceaeEscherichia
Proteomesi
  • UP000000318 Componenti: Chromosome
  • UP000000625 Componenti: Chromosome

Organism-specific databases

EcoGeneiEG11090 pfs

Subcellular locationi

GO - Cellular componenti

  • cytosol Source: EcoCyc

Pathology & Biotechi

Mutagenesis

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Mutagenesisi9M → A: 13-19% of wild-type catalytic efficiency. 1 Publication1
Mutagenesisi12E → A or Q: Loss of catalytic activity. 1 Publication1
Mutagenesisi50I → A: 12-23% of wild-type catalytic efficiency. 1 Publication1
Mutagenesisi76S → A: 13-23% of wild-type catalytic efficiency. 1 Publication1
Mutagenesisi151F → A: 0.5% of wild-type catalytic efficiency. 1 Publication1
Mutagenesisi173M → A: 0.5% of wild-type catalytic efficiency. 1 Publication1
Mutagenesisi174E → A or Q: Loss of catalytic activity. 1 Publication1
Mutagenesisi193R → A: 13-28% of wild-type catalytic efficiency. 1 Publication1
Mutagenesisi196S → A: 2-4% of wild-type catalytic efficiency. 1 Publication1
Mutagenesisi197D → A or N: Loss of catalytic activity. 1 Publication1
Mutagenesisi207F → A: 2% of wild-type catalytic efficiency. 1 Publication1

Chemistry databases

ChEMBLiCHEMBL2866
DrugBankiDB02933 5'-Deoxy-5'-(Methylthio)-Tubercidin
DB00173 Adenine
DB02281 Formycin

PTM / Processingi

Molecule processing

Feature keyPosition(s)DescriptionActionsGraphical viewLength
ChainiPRO_00001644391 – 2325'-methylthioadenosine/S-adenosylhomocysteine nucleosidaseAdd BLAST232

Proteomic databases

EPDiP0AF12
PaxDbiP0AF12
PRIDEiP0AF12

2D gel databases

SWISS-2DPAGEiP0AF12

Interactioni

Subunit structurei

Homodimer.4 Publications

Binary interactionsi

WithEntry#Exp.IntActNotes
itself2EBI-1114261,EBI-1114261

GO - Molecular functioni

  • identical protein binding Source: IntAct

Protein-protein interaction databases

BioGridi4260991, 38 interactors
DIPiDIP-10270N
IntActiP0AF12, 7 interactors
STRINGi316385.ECDH10B_0139

Chemistry databases

BindingDBiP0AF12

Structurei

Secondary structure

1232
Legend: HelixTurnBeta strandPDB Structure known for this area
Show more details
Feature keyPosition(s)DescriptionActionsGraphical viewLength
Beta strandi2 – 9Combined sources8
Helixi10 – 17Combined sources8
Beta strandi21 – 28Combined sources8
Beta strandi31 – 38Combined sources8
Beta strandi41 – 47Combined sources7
Helixi52 – 66Combined sources15
Beta strandi69 – 79Combined sources11
Beta strandi89 – 99Combined sources11
Helixi103 – 105Combined sources3
Beta strandi117 – 120Combined sources4
Helixi123 – 135Combined sources13
Beta strandi140 – 147Combined sources8
Helixi155 – 164Combined sources10
Beta strandi168 – 174Combined sources7
Helixi175 – 185Combined sources11
Beta strandi189 – 197Combined sources9
Helixi203 – 231Combined sources29

3D structure databases

Select the link destinations:
PDBei
RCSB PDBi
PDBji
Links Updated
PDB entryMethodResolution (Å)ChainPositionsPDBsum
1JYSX-ray1.90A/B1-232[»]
1NC1X-ray2.00A/B1-232[»]
1NC3X-ray2.20A/B1-232[»]
1Y6QX-ray2.20A/B1-232[»]
1Y6RX-ray2.20A/B1-232[»]
1Z5NX-ray2.10A/B1-232[»]
1Z5OX-ray2.00A/B1-232[»]
1Z5PX-ray2.00A1-232[»]
3O4VX-ray1.75A/B1-232[»]
4WKCX-ray1.64A1-232[»]
4YMLX-ray1.75A1-232[»]
ProteinModelPortaliP0AF12
SMRiP0AF12
ModBaseiSearch...
MobiDBiSearch...

Miscellaneous databases

EvolutionaryTraceiP0AF12

Family & Domainsi

Region

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Regioni173 – 174Substrate binding2

Sequence similaritiesi

Phylogenomic databases

eggNOGiENOG4105DUF Bacteria
COG0775 LUCA
HOGENOMiHOG000259346
InParanoidiP0AF12
KOiK01243
OMAiDQFVHSK
PhylomeDBiP0AF12

Family and domain databases

HAMAPiMF_01684 Salvage_MtnN, 1 hit
InterProiView protein in InterPro
IPR010049 MTA_SAH_Nsdase
IPR000845 Nucleoside_phosphorylase_d
IPR035994 Nucleoside_phosphorylase_sf
PfamiView protein in Pfam
PF01048 PNP_UDP_1, 1 hit
SUPFAMiSSF53167 SSF53167, 1 hit
TIGRFAMsiTIGR01704 MTA/SAH-Nsdase, 1 hit

Sequencei

Sequence statusi: Complete.

P0AF12-1 [UniParc]FASTAAdd to basket

« Hide

        10         20         30         40         50
MKIGIIGAME EEVTLLRDKI ENRQTISLGG CEIYTGQLNG TEVALLKSGI
60 70 80 90 100
GKVAAALGAT LLLEHCKPDV IINTGSAGGL APTLKVGDIV VSDEARYHDA
110 120 130 140 150
DVTAFGYEYG QLPGCPAGFK ADDKLIAAAE ACIAELNLNA VRGLIVSGDA
160 170 180 190 200
FINGSVGLAK IRHNFPQAIA VEMEATAIAH VCHNFNVPFV VVRAISDVAD
210 220 230
QQSHLSFDEF LAVAAKQSSL MVESLVQKLA HG
Length:232
Mass (Da):24,354
Last modified:December 20, 2005 - v1
Checksum:i9B1FF9BEC39D4F2C
GO

Sequence cautioni

The sequence AAA23678 differs from that shown. Reason: Erroneous initiation.Curated

Experimental Info

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Sequence conflicti212 – 232AVAAK…KLAHG → LLPLNSPA in AAA23678 (PubMed:2157212).CuratedAdd BLAST21
Sequence conflicti212 – 232AVAAK…KLAHG → LLPLNSPA in AAA24322 (PubMed:2157212).CuratedAdd BLAST21

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
M31772 Genomic DNA Translation: AAA23678.1 Different initiation.
U24438 Genomic DNA Translation: AAC38291.1
M83735 Genomic DNA Translation: AAA24322.1
U70214 Genomic DNA Translation: AAB08589.1
U00096 Genomic DNA Translation: AAC73270.1
AP009048 Genomic DNA Translation: BAB96736.1
PIRiS45227
RefSeqiNP_414701.1, NC_000913.3
WP_000689844.1, NZ_LN832404.1

Genome annotation databases

EnsemblBacteriaiAAC73270; AAC73270; b0159
BAB96736; BAB96736; BAB96736
GeneIDi948542
KEGGiecj:JW0155
eco:b0159
PATRICifig|1411691.4.peg.2121

Entry informationi

Entry nameiMTNN_ECOLI
AccessioniPrimary (citable) accession number: P0AF12
Secondary accession number(s): P24247
Entry historyiIntegrated into UniProtKB/Swiss-Prot: December 20, 2005
Last sequence update: December 20, 2005
Last modified: March 28, 2018
This is version 110 of the entry and version 1 of the sequence. See complete history.
Entry statusiReviewed (UniProtKB/Swiss-Prot)
Annotation programProkaryotic Protein Annotation Program

Miscellaneousi

Keywords - Technical termi

3D-structure, Complete proteome, Reference proteome

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