P0AF12 · MTNN_ECOLI
- Protein5'-methylthioadenosine/S-adenosylhomocysteine nucleosidase
- GenemtnN
- StatusUniProtKB reviewed (Swiss-Prot)
- Organism
- Amino acids232 (go to sequence)
- Protein existenceEvidence at protein level
- Annotation score5/5
Function
function
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 (PubMed:16101288, PubMed:3911944).
Also cleaves 5'-deoxyadenosine, a toxic by-product of radical S-adenosylmethionine (SAM) enzymes, into 5-deoxyribose and adenine. Thus, is required for in vivo function of the radical SAM enzymes biotin synthase and lipoic acid synthase, that are inhibited by 5'-deoxyadenosine accumulation (PubMed:15911379).
Can also use 5'-isobutylthioadenosine, 5'-n-butylthioadenosine, S-adenosyl-D-homocysteine, decarboxylated adenosylhomocysteine, deaminated adenosylhomocysteine and S-2-aza-adenosylhomocysteine as substrates in vitro (PubMed:3911944).
Also cleaves 5'-deoxyadenosine, a toxic by-product of radical S-adenosylmethionine (SAM) enzymes, into 5-deoxyribose and adenine. Thus, is required for in vivo function of the radical SAM enzymes biotin synthase and lipoic acid synthase, that are inhibited by 5'-deoxyadenosine accumulation (PubMed:15911379).
Can also use 5'-isobutylthioadenosine, 5'-n-butylthioadenosine, S-adenosyl-D-homocysteine, decarboxylated adenosylhomocysteine, deaminated adenosylhomocysteine and S-2-aza-adenosylhomocysteine as substrates in vitro (PubMed:3911944).
Catalytic activity
- H2O + S-adenosyl-L-homocysteine = adenine + S-(5-deoxy-D-ribos-5-yl)-L-homocysteine
Activity regulation
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.
Kinetics
KM | SUBSTRATE | pH | TEMPERATURE[C] | NOTES | EVIDENCE | |
---|---|---|---|---|---|---|
0.4 μM | 5'-methylthioadenosine | 7 | 37 | |||
0.8 μM | 5'-methylthioadenosine | 7 | 22 | |||
4.3 μM | S-adenosylhomocysteine | 7 | 37 | |||
1.3 μM | S-adenosylhomocysteine | 7 | 22 |
kcat is 3.0 sec-1 and 2.6 sec-1 with 5'-methylthioadenosine and S-adenosylhomocysteine as substrate, respectively.
pH Dependence
Exhibits activity across a broad pH range. Enzyme activity is moderately improved under acidic conditions.
Temperature Dependence
Optimum temperature is 37-45 degrees Celsius. Rapidly inactivated after exposure for 10 minutes at 55 degrees Celsius.
Pathway
Amino-acid biosynthesis; L-methionine biosynthesis via salvage pathway; S-methyl-5-thio-alpha-D-ribose 1-phosphate from S-methyl-5'-thioadenosine (hydrolase route): step 1/2.
Features
Showing features for active site, binding site.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Active site | 12 | Proton acceptor | ||||
Sequence: E | ||||||
Binding site | 78 | substrate | ||||
Sequence: G | ||||||
Binding site | 152 | substrate | ||||
Sequence: I | ||||||
Binding site | 173-174 | substrate | ||||
Sequence: ME | ||||||
Active site | 197 | Proton donor | ||||
Sequence: D |
GO annotations
Aspect | Term | |
---|---|---|
Cellular Component | cytosol | |
Molecular Function | adenosylhomocysteine nucleosidase activity | |
Molecular Function | identical protein binding | |
Molecular Function | methylthioadenosine nucleosidase activity | |
Molecular Function | protein homodimerization activity | |
Biological Process | L-methionine salvage from methylthioadenosine | |
Biological Process | L-methionine salvage from S-adenosylmethionine | |
Biological Process | purine deoxyribonucleoside catabolic process | |
Biological Process | toxic metabolite repair |
Keywords
- Molecular function
- Biological process
Enzyme and pathway databases
Names & Taxonomy
Protein names
- Recommended name5'-methylthioadenosine/S-adenosylhomocysteine nucleosidase
- EC number
- Short namesMTA/SAH nucleosidase ; MTAN
- Alternative names
Gene names
Organism names
- Organism
- Strains
- Taxonomic lineageBacteria > Pseudomonadota > Gammaproteobacteria > Enterobacterales > Enterobacteriaceae > Escherichia
Accessions
- Primary accessionP0AF12
- Secondary accessions
Proteomes
Subcellular Location
UniProt Annotation
GO Annotation
Phenotypes & Variants
Disruption phenotype
Cells lacking this gene are deficient in biotin synthase (BioB) activity in vivo due to accumulation of 5'-deoxyadenosine.
Features
Showing features for mutagenesis.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Mutagenesis | 9 | 13-19% of wild-type catalytic efficiency. | ||||
Sequence: M → A | ||||||
Mutagenesis | 12 | Loss of catalytic activity. | ||||
Sequence: E → A or Q | ||||||
Mutagenesis | 50 | 12-23% of wild-type catalytic efficiency. | ||||
Sequence: I → A | ||||||
Mutagenesis | 76 | 13-23% of wild-type catalytic efficiency. | ||||
Sequence: S → A | ||||||
Mutagenesis | 151 | 0.5% of wild-type catalytic efficiency. | ||||
Sequence: F → A | ||||||
Mutagenesis | 173 | 0.5% of wild-type catalytic efficiency. | ||||
Sequence: M → A | ||||||
Mutagenesis | 174 | Loss of catalytic activity. | ||||
Sequence: E → A or Q | ||||||
Mutagenesis | 193 | 13-28% of wild-type catalytic efficiency. | ||||
Sequence: R → A | ||||||
Mutagenesis | 196 | 2-4% of wild-type catalytic efficiency. | ||||
Sequence: S → A | ||||||
Mutagenesis | 197 | Loss of catalytic activity. | ||||
Sequence: D → A or N | ||||||
Mutagenesis | 207 | 2% of wild-type catalytic efficiency. | ||||
Sequence: F → A |
Chemistry
PTM/Processing
Features
Showing features for chain.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Chain | PRO_0000164439 | 1-232 | 5'-methylthioadenosine/S-adenosylhomocysteine nucleosidase | |||
Sequence: MKIGIIGAMEEEVTLLRDKIENRQTISLGGCEIYTGQLNGTEVALLKSGIGKVAAALGATLLLEHCKPDVIINTGSAGGLAPTLKVGDIVVSDEARYHDADVTAFGYEYGQLPGCPAGFKADDKLIAAAEACIAELNLNAVRGLIVSGDAFINGSVGLAKIRHNFPQAIAVEMEATAIAHVCHNFNVPFVVVRAISDVADQQSHLSFDEFLAVAAKQSSLMVESLVQKLAHG |
Proteomic databases
Interaction
Subunit
Homodimer.
Binary interactions
Type | Entry 1 | Entry 2 | Number of experiments | Intact | |
---|---|---|---|---|---|
BINARY | P0AF12 | mtnN P0AF12 | 2 | EBI-1114261, EBI-1114261 |
Protein-protein interaction databases
Chemistry
Structure
Sequence
- Sequence statusComplete
- Length232
- Mass (Da)24,354
- Last updated2005-12-20 v1
- Checksum9B1FF9BEC39D4F2C
Sequence caution
Features
Showing features for sequence conflict.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Sequence conflict | 212-232 | in Ref. 1; AAA23678/AAA24322 | ||||
Sequence: AVAAKQSSLMVESLVQKLAHG → LLPLNSPA |
Keywords
- Technical term
Sequence databases
Nucleotide Sequence | Protein Sequence | Molecule Type | Status | |
---|---|---|---|---|
M31772 EMBL· GenBank· DDBJ | AAA23678.1 EMBL· GenBank· DDBJ | Genomic DNA | Different initiation | |
U24438 EMBL· GenBank· DDBJ | AAC38291.1 EMBL· GenBank· DDBJ | Genomic DNA | ||
M83735 EMBL· GenBank· DDBJ | AAA24322.1 EMBL· GenBank· DDBJ | Genomic DNA | ||
U70214 EMBL· GenBank· DDBJ | AAB08589.1 EMBL· GenBank· DDBJ | Genomic DNA | ||
U00096 EMBL· GenBank· DDBJ | AAC73270.1 EMBL· GenBank· DDBJ | Genomic DNA | ||
AP009048 EMBL· GenBank· DDBJ | BAB96736.1 EMBL· GenBank· DDBJ | Genomic DNA |