SsuD-SsuE complex
A protein complex containing an alkanesulfonate monooxygenase subunit (SsuD tetramer in E. coli) and a flavin oxidoreductase subunit (SsuE dimer in E. coli). Involved in the utilization of alkanesulfonates as sulfur sources under conditions of sulfate or cysteine starvation. [GO:1990200]
Synonyms: two-component alkanesulfonate monooxygenase system
Components
| Component | Type | Part of / acts on | Grounding | Genes | Stoichiometry | Essential | Role |
|---|---|---|---|---|---|---|---|
| SsuD alkanesulfonate monooxygenase | Protein | part of | Reviewed label only (reviewed name; no accession asserted) | ssuD | UNKNOWN | FMNH2-dependent monooxygenase constituent that oxygenates alkanesulfonates to release sulfite and the corresponding aldehyde.
| |
| NADPH-dependent FMN reductase SsuE | Protein | part of | InterPro:IPR020048 | ssuE | UNKNOWN | FMN reductase constituent that provides reduced FMN to SsuD for alkanesulfonate monooxygenase catalysis.
|
Organism-specific protein examples
Named proteins in which each component's role was established, with the organism the evidence comes from. The component above is the taxon-agnostic family; these are the specific entries behind it.
SsuD alkanesulfonate monooxygenase
| Accession | Protein | Gene | Organism | Entry |
|---|---|---|---|---|
UniProtKB:P80645 | Alkanesulfonate monooxygenase | ssuD | Escherichia coli K-12 (NCBITaxon:83333) | REVIEWED |
Role and evidence (2 references)Reviewed E. coli K-12 SsuD accession for the alkanesulfonate monooxygenase subunit characterized in the two-component system.
| ||||
NADPH-dependent FMN reductase SsuE
| Accession | Protein | Gene | Organism | Entry |
|---|---|---|---|---|
UniProtKB:P80644 | FMN reductase (NADPH) | ssuE | Escherichia coli K-12 (NCBITaxon:83333) | REVIEWED |
Role and evidence (2 references)Reviewed E. coli K-12 SsuE accession for the FMN reductase subunit characterized in the two-component system.
| ||||
Taxonomic distribution
NCBITaxon:562Escherichia coli — COMMON: The GO-cited biochemical studies defined the SsuD-SsuE complex using Escherichia coli SsuD and SsuE. [PMID:16997955]
Canonical examples
NCBITaxon:562Escherichia coli — Gao and Ellis 2006 used E. coli SsuD and SsuE to detect a stable protein-protein complex in the alkanesulfonate monooxygenase system. [PMID:16997955]
Functions
- alkanesulfonate monooxygenase activity
GO:0008726— The complex couples SsuE-dependent FMN reduction to SsuD-catalyzed FMNH2-dependent oxygenation of alkanesulfonates, generating sulfite and aldehyde products during sulfur starvation.GO:0008726GO:0008726 is the molecular-function term for alkanesulfonate monooxygenase activity.PMID:10480865Eichhorn et al. 1999 showed that SsuE supplies reduced FMN and SsuD catalyzes oxygenolytic alkanesulfonate conversion.
Discussions
- CURATION_TODO (OPEN): Resolve an exact source-neutral family grounding for SsuD alkanesulfonate monooxygenase. The first record represents SsuD by its reviewed E. coli gene name and avoids mapping it to InterPro:IPR050172 because that family also covers RutA monooxygenases.
- INTERPRETATION (RESOLVED): Should the SsuD-SsuE complex assert a fixed six-subunit stoichiometry? No. The first biochemical study characterized isolated SsuD as a homotetramer and isolated SsuE as a homodimer, while the later interaction study supported a stable SsuD-SsuE complex and proposed a 1:1 monomeric SsuE:SsuD association. This record leaves the assembled complex subunit count unmodeled.
Evidence
GO:1990200Gene Ontology cellular-component term for the SsuD-SsuE complex and its related two-component alkanesulfonate monooxygenase system synonym.GO:0032991QuickGO reports GO:1990200 SsuD-SsuE complex as an is-a child of GO:0032991 protein-containing complex.GO:0008726Gene Ontology molecular-function term for alkanesulfonate monooxygenase activity.InterPro:IPR020048InterPro family entry for NADPH-dependent FMN reductase, SsuE.InterPro:IPR050172InterPro family entry for SsuD/RutA monooxygenases; this broad entry was not used as exact grounding for the SsuD component.UniProtKB:P80645UniProtKB reviewed E. coli K-12 SsuD entry.UniProtKB:P80644UniProtKB reviewed E. coli K-12 SsuE entry.PMID:10480865PubMed identifier for Eichhorn, van der Ploeg and Leisinger 1999, the Journal of Biological Chemistry SsuD/SsuE characterization paper cited by GO:1990201.DOI:10.1074/jbc.274.38.26639DOI for Eichhorn, van der Ploeg and Leisinger 1999, 'Characterization of a two-component alkanesulfonate monooxygenase from Escherichia coli', as reported by PubMed.PMID:16997955PubMed identifier for Gao and Ellis 2006, the Journal of Bacteriology SsuD-SsuE interaction paper cited by GO:1990200.DOI:10.1128/JB.00966-06DOI for Gao and Ellis 2006, 'Detection of protein-protein interactions in the alkanesulfonate monooxygenase system from Escherichia coli', as reported by PubMed.
Curation history
2026-10-01T17:44:17Zcodex · CREATED_RECORD — Scaffolded by scripts/new_record.py2026-10-01T17:45:38Zcodex · EXPANDED_RECORD — Added the GO synonym and protein-containing-complex parent, curated SsuD and SsuE constituents with E. coli K-12 reviewed UniProt examples, grounded SsuE to InterPro, added alkanesulfonate monooxygenase function and E. coli example evidence, and recorded grounding and stoichiometry boundary decisions.