A0A411MR89 · SZNF_STRC2
- ProteinNitrosourea synthase
- GenesznF
- StatusUniProtKB reviewed (Swiss-Prot)
- Amino acids471 (go to sequence)
- Protein existenceEvidence at protein level
- Annotation score5/5
Function
function
Involved in the biosynthesis of the glucosamine-nitrosourea antibiotic streptozotocin (SZN) (PubMed:30728519, PubMed:30763082).
Catalyzes a complex multi-step reaction: the overall reaction is an oxidative rearrangement of the guanidine group of N(omega)-methyl-L-arginine (L-NMA), generating an N-nitrosourea product (PubMed:30728519, PubMed:30763082, PubMed:32511919).
SznF first hydroxylates L-NMA to form N(delta)-hydroxy-N(omega)-methyl-L-arginine (L-HMA), which is further hydroxylated to give N(delta)-hydroxy-N(omega)-hydroxy-N(omega)-methyl-L-arginine (L-DHMA) (PubMed:30728519, PubMed:32511919).
Subsequently, an oxidative rearrangement converts this intermediate to N(delta)-hydroxy-N(omega)-methyl-N(omega)-nitroso-L-citrulline (PubMed:30728519, PubMed:34004115).
This product is unstable, and degrades non-enzymically into nitric oxide and the denitrosated product N(delta)-hydroxy-N(omega)-methyl-L-citrulline (PubMed:30728519).
Catalyzes a complex multi-step reaction: the overall reaction is an oxidative rearrangement of the guanidine group of N(omega)-methyl-L-arginine (L-NMA), generating an N-nitrosourea product (PubMed:30728519, PubMed:30763082, PubMed:32511919).
SznF first hydroxylates L-NMA to form N(delta)-hydroxy-N(omega)-methyl-L-arginine (L-HMA), which is further hydroxylated to give N(delta)-hydroxy-N(omega)-hydroxy-N(omega)-methyl-L-arginine (L-DHMA) (PubMed:30728519, PubMed:32511919).
Subsequently, an oxidative rearrangement converts this intermediate to N(delta)-hydroxy-N(omega)-methyl-N(omega)-nitroso-L-citrulline (PubMed:30728519, PubMed:34004115).
This product is unstable, and degrades non-enzymically into nitric oxide and the denitrosated product N(delta)-hydroxy-N(omega)-methyl-L-citrulline (PubMed:30728519).
Catalytic activity
- N(omega)-methyl-L-arginine + 2 NADH + 3 O2 + H+ = N(delta)-hydroxy-N(omega)-methyl-N(omega)-nitroso-L-citrulline + 2 NAD+ + 3 H2OThis reaction proceeds in the forward direction.
- N(omega)-methyl-L-arginine + NADH + O2 + H+ = N(delta)-hydroxy-N(omega)-methyl-L-arginine + NAD+ + H2OThis reaction proceeds in the forward direction.
- N(delta)-hydroxy-N(omega)-methyl-L-arginine + NADH + O2 = N(delta),N(omega')-dihydroxy-N(omega)-methyl-L-arginine + NAD+ + H2OThis reaction proceeds in the forward direction.
- N(delta),N(omega')-dihydroxy-N(omega)-methyl-L-arginine + O2 = N(delta)-hydroxy-N(omega)-methyl-N(omega)-nitroso-L-citrulline + H2OThis reaction proceeds in the forward direction.
- 2 N(delta)-hydroxy-N(omega)-methyl-N(omega)-nitroso-L-citrulline + AH2 = 2 N(delta)-hydroxy-N(omega)-methyl-L-citrulline + 2 nitric oxide + AThis reaction proceeds in the forward direction.
Cofactor
pH Dependence
Stable and active at pH 3-8, but loses its activity above pH 9 (PubMed:30763082).
Shows reduced activity in phosphate buffer at pH 4-6 (PubMed:30763082).
Shows reduced activity in phosphate buffer at pH 4-6 (PubMed:30763082).
Pathway
Antibiotic biosynthesis.
Features
Showing features for binding site.
Type | ID | Position(s) | Description | ||
---|---|---|---|---|---|
Binding site | 189 | Fe2+ 1 (UniProtKB | ChEBI) | |||
Binding site | 215 | Fe2+ 1 (UniProtKB | ChEBI) | |||
Binding site | 215 | Fe2+ 2 (UniProtKB | ChEBI) | |||
Binding site | 225 | Fe2+ 1 (UniProtKB | ChEBI) | |||
Binding site | 281 | Fe2+ 2 (UniProtKB | ChEBI) | |||
Binding site | 311 | Fe2+ 1 (UniProtKB | ChEBI) | |||
Binding site | 315 | Fe2+ 2 (UniProtKB | ChEBI) | |||
Binding site | 318 | Fe2+ 2 (UniProtKB | ChEBI) | |||
Binding site | 407 | Fe2+ 3 (UniProtKB | ChEBI) | |||
Binding site | 409 | Fe2+ 3 (UniProtKB | ChEBI) | |||
Binding site | 448 | Fe2+ 3 (UniProtKB | ChEBI) | |||
GO annotations
Aspect | Term | |
---|---|---|
Molecular Function | metal ion binding | |
Molecular Function | monooxygenase activity | |
Biological Process | antibiotic biosynthetic process |
Keywords
- Molecular function
- Biological process
- Ligand
Enzyme and pathway databases
Names & Taxonomy
Protein names
- Recommended nameNitrosourea synthase
- EC number
- Alternative names
Gene names
Organism names
- Strains
- Taxonomic lineageBacteria > Actinomycetota > Actinomycetes > Kitasatosporales > Streptomycetaceae > Streptomyces
Accessions
- Primary accessionA0A411MR89
Phenotypes & Variants
Disruption phenotype
Deletion of the gene abolishes SZN production (PubMed:30728519, PubMed:30763082).
Mutant accumulates L-NMA (PubMed:30728519).
Mutant accumulates L-NMA (PubMed:30728519).
Features
Showing features for mutagenesis.
Type | ID | Position(s) | Description | ||
---|---|---|---|---|---|
Mutagenesis | 214-215 | Loss of activity. | |||
Mutagenesis | 215 | Loss of activity. | |||
Mutagenesis | 225 | Loss of activity. | |||
Mutagenesis | 281 | Loss of activity. | |||
Mutagenesis | 311 | Loss of activity. | |||
Mutagenesis | 315 | Loss of activity. | |||
Mutagenesis | 318 | Loss of activity. | |||
Mutagenesis | 407 | Accumulates the intermediate L-DHMA, but cannot form the final product; when associated with A-409 and A-448. | |||
Mutagenesis | 409 | Accumulates the intermediate L-DHMA, but cannot form the final product; when associated with A-407 and A-448. | |||
Mutagenesis | 448 | Accumulates the intermediate L-DHMA, but cannot form the final product; when associated with A-407 and A-409. | |||
PTM/Processing
Features
Showing features for chain.
Type | ID | Position(s) | Description | ||
---|---|---|---|---|---|
Chain | PRO_0000457552 | 1-471 | Nitrosourea synthase | ||
Interaction
Subunit
Homodimer.
Structure
Family & Domains
Features
Showing features for region.
Type | ID | Position(s) | Description | ||
---|---|---|---|---|---|
Region | 177-328 | HO-like | |||
Region | 397-459 | Cupin | |||
Domain
Contains three distinc domains: N-terminal helical motifs involved in dimerization, followed by a heme-oxygenase-like (HO-like) central domain and a C-terminal monoiron cupin domain (PubMed:30728519, PubMed:33468680).
The central domain catalyzes the two sequential N-hydroxylations of L-NMA and the cupin domain enables oxidative rearrangement and N-N bond formation to yield the N-nitrosourea product (PubMed:30728519).
The central HO-like domain can bind Fe2+ and use it to capture O2, forming a peroxo-Fe2(III/III) intermediate, which is an intermediate in both hydroxylation steps (PubMed:32511919).
Structural changes accompany diiron cofactor assembly in the HO-like domain (PubMed:33468680).
The central domain catalyzes the two sequential N-hydroxylations of L-NMA and the cupin domain enables oxidative rearrangement and N-N bond formation to yield the N-nitrosourea product (PubMed:30728519).
The central HO-like domain can bind Fe2+ and use it to capture O2, forming a peroxo-Fe2(III/III) intermediate, which is an intermediate in both hydroxylation steps (PubMed:32511919).
Structural changes accompany diiron cofactor assembly in the HO-like domain (PubMed:33468680).
Family and domain databases
Sequence
- Sequence statusComplete
- Length471
- Mass (Da)53,802
- Last updated2019-05-08 v1
- Checksum0122DFCB07B29B3D
Keywords
- Technical term
Sequence databases
Nucleotide Sequence | Protein Sequence | Molecule Type | Status | |
---|---|---|---|---|
MK291260 EMBL· GenBank· DDBJ | QBA82042.1 EMBL· GenBank· DDBJ | Genomic DNA | ||
MK303572 EMBL· GenBank· DDBJ | QBA82202.1 EMBL· GenBank· DDBJ | Genomic DNA | ||
MK440296 EMBL· GenBank· DDBJ | QBF29330.1 EMBL· GenBank· DDBJ | Genomic DNA |