A0A411MR89 · SZNF_STRC2

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).

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 H2O
    This reaction proceeds in the forward direction.
    EC:1.14.13.250 (UniProtKB | ENZYME | Rhea)
  • N(omega)-methyl-L-arginine + NADH + O2 + H+ = N(delta)-hydroxy-N(omega)-methyl-L-arginine + NAD+ + H2O
    This 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+ + H2O
    This 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 + H2O
    This 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 + A
    This reaction proceeds in the forward direction.

Cofactor

Fe2+ (UniProtKB | Rhea| CHEBI:29033 )

Note: Binds 3 Fe2+ ions per subunit (PubMed:33468680).
Two Fe2+ bind the HO-like central domain and one Fe2+ binds the C-terminal cupin domain (PubMed:33468680).

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).

Pathway

Antibiotic biosynthesis.

Features

Showing features for binding site.

TypeIDPosition(s)Description
Binding site189Fe2+ 1 (UniProtKB | ChEBI)
Binding site215Fe2+ 1 (UniProtKB | ChEBI)
Binding site215Fe2+ 2 (UniProtKB | ChEBI)
Binding site225Fe2+ 1 (UniProtKB | ChEBI)
Binding site281Fe2+ 2 (UniProtKB | ChEBI)
Binding site311Fe2+ 1 (UniProtKB | ChEBI)
Binding site315Fe2+ 2 (UniProtKB | ChEBI)
Binding site318Fe2+ 2 (UniProtKB | ChEBI)
Binding site407Fe2+ 3 (UniProtKB | ChEBI)
Binding site409Fe2+ 3 (UniProtKB | ChEBI)
Binding site448Fe2+ 3 (UniProtKB | ChEBI)

GO annotations

AspectTerm
Molecular Functionmetal ion binding
Molecular Functionmonooxygenase activity
Biological Processantibiotic biosynthetic process

Keywords

Enzyme and pathway databases

Names & Taxonomy

Protein names

  • Recommended name
    Nitrosourea synthase
  • EC number
  • Alternative names
    • Multi-domain metalloenzyme SznF

Gene names

    • Name
      sznF
    • Synonyms
      stzF

Organism names

Accessions

  • Primary accession
    A0A411MR89

Phenotypes & Variants

Disruption phenotype

Deletion of the gene abolishes SZN production (PubMed:30728519, PubMed:30763082).
Mutant accumulates L-NMA (PubMed:30728519).

Features

Showing features for mutagenesis.

TypeIDPosition(s)Description
Mutagenesis214-215Loss of activity.
Mutagenesis215Loss of activity.
Mutagenesis225Loss of activity.
Mutagenesis281Loss of activity.
Mutagenesis311Loss of activity.
Mutagenesis315Loss of activity.
Mutagenesis318Loss of activity.
Mutagenesis407Accumulates the intermediate L-DHMA, but cannot form the final product; when associated with A-409 and A-448.
Mutagenesis409Accumulates the intermediate L-DHMA, but cannot form the final product; when associated with A-407 and A-448.
Mutagenesis448Accumulates 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.

TypeIDPosition(s)Description
ChainPRO_00004575521-471Nitrosourea synthase

Interaction

Subunit

Homodimer.

Family & Domains

Features

Showing features for region.

TypeIDPosition(s)Description
Region177-328HO-like
Region397-459Cupin

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).

Family and domain databases

Sequence

  • Sequence status
    Complete
  • Length
    471
  • Mass (Da)
    53,802
  • Last updated
    2019-05-08 v1
  • Checksum
    0122DFCB07B29B3D
MSHVPPHVPFELSGAELRDAIVQYATNPIYHDNLDWLNHDNPYRRQLRPQVLPHLDYDKVPGRENILNYASLAVQRLLTSVYEADLVFFPKSGLKGKEEDFRAFYSPANRALGERIRPALERYAFGFLDDEVETSGTWTAQSLDAYLDSLDTAGGAEQSPVEKAILGSADRERAARMWLVQFAPDFLSEASPMMRNVLGYYGPAQSEWFKVVIDEYGYGVHDTKHSTLFERTLESVGLESDLHRYWQYYLNSSLLLNNYFHYLGKNHELFFRYVGALYYTESSLVDFCRRADHLLREVFGDTVDTTYFTEHIHIDQHHGRMAREKIIKPLVEAHGDGIIPEIVRGIEEYRVLLEIGDFDFSEQIAWMDAQPELKKLHDPVFEGLKQGKVDAPVAHLVEPRGELSNTHCHDGDELCHIVSGTMRFESGLGSSLTLQAGEGVVIKRNRLHGANIESDECVYEIHSVGDYRKCL

Keywords

Sequence databases

Nucleotide SequenceProtein SequenceMolecule TypeStatus
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

Genome annotation databases

Similar Proteins

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