sfgA (suppressor of fluG) encodes a nuclear Gal4-type Zn(II)2Cys6 binuclear-cluster DNA-binding protein that acts as a negative regulator of asexual sporulation (conidiation) and sterigmatocystin production in Aspergillus nidulans. Loss-of-function sfgA mutations bypass the requirement for fluG in both processes, and overexpression of sfgA inhibits conidiation and delays conidiation- and ST-specific gene expression, showing that FluG acts by removing SfgA-imposed repression rather than by direct activation. Genetically SfgA functions downstream of FluG and upstream of the transcriptional activators FlbD, FlbC, FlbB and BrlA that drive normal conidiophore development.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000976 transcription cis-regulatory region binding | IEA GO_REF:0000118 | ACCEPT | Summary: Accept: transcription cis-regulatory region binding. Reason: Zn(II)2Cys6 binuclear-cluster factors bind upstream activating and repressing sequences, so the prediction fits SfgA's domain. No SfgA DNA-binding assay is cited in this review, so the row rests on the domain call. |
| GO:0000981 DNA-binding transcription factor activity, RNA polymerase II-specific | IEA GO_REF:0000002 | ACCEPT | Summary: Accept: DNA-binding transcription factor activity, RNA polymerase II-specific. Reason: Pol II-specific TF activity predicted from the binuclear-cluster domain, and consistent with SfgA acting as a repressor whose removal is what permits FluG-dependent development. |
| GO:0003677 DNA binding | IEA GO_REF:0000104 | ACCEPT | Summary: Accept: DNA binding. Reason: Unsigned keyword-level parent of the terms above; uninformative on its own. |
| GO:0003700 DNA-binding transcription factor activity | IEA GO_REF:0000118 | ACCEPT | Summary: Accept: DNA-binding transcription factor activity. Reason: General TF term, subsumed by the Pol II-specific call; kept as its parent. |
| GO:0005634 nucleus | IEA GO_REF:0000120 | ACCEPT | Summary: Accept: nucleus. Reason: Expected compartment for a sequence-specific DNA-binding regulator, and the ARBA rule behind this call is recorded as the SUBCELLULAR LOCATION in the UniProt entry (sfgA-uniprot.txt:24). Note this remains a prediction - the primary sfgA paper is genetic and does not image SfgA localization. |
| GO:0006351 DNA-templated transcription | IEA GO_REF:0000104 | KEEP AS NON CORE | Summary: Borderline: SfgA regulates transcription rather than catalyzing it. Reason: 'DNA-templated transcription' implies performing transcription; for a TF the regulation terms are preferred. |
| GO:0006355 regulation of DNA-templated transcription | IEA GO_REF:0000120 | ACCEPT | Summary: Accept: regulation of DNA-templated transcription. Reason: Generic unsigned process parent. SfgA's characterised role is repression relieved by FluG signalling, so a signed negative-regulation term would be more informative than this one. |
| GO:0008270 zinc ion binding | IEA GO_REF:0000002 | ACCEPT | Summary: Accept: zinc ion binding. Reason: The Gal4-type Zn(II)2Cys6 binuclear cluster is a zinc-coordinating fold by definition, and the motif is identified in SfgA directly (PMID:16387865) rather than only inferred from InterPro. Supporting Evidence: PMID:16387865 novel protein with the Gal4-type Zn(II) 2 Cys 6 binuclear cluster DNA-binding motif at the N terminus |
| GO:0045944 positive regulation of transcription by RNA polymerase II | IEA GO_REF:0000118 | MARK AS OVER ANNOTATED | Summary: Direction-specific term contradicted by the characterized biology; SfgA is a repressor, not an activator. Reason: This is an IEA:TreeGrafter propagation from the PTHR37534 zinc-cluster family (whose named member is the transcriptional *activator* Uga3), not an SfgA-specific inference. The primary characterization of sfgA shows the opposite direction - loss of sfgA bypasses fluG and derepresses conidiation, and sfgA overexpression inhibits it - so a positive-regulation term over-propagates the family's activator role onto a repressor. The direction-neutral GO:0006355 already retained here covers what is safely supportable; if a directional MF is wanted, GO:0001227 (DNA-binding transcription repressor activity, RNA polymerase II-specific) would be the correctly signed term. Supporting Evidence: PMID:16387865 In accordance with the proposed regulatory role of SfgA, overexpression of sfgA inhibited conidiation and delayed/reduced expression of conidiation- and ST-specific genes. |
| GO:0075308 negative regulation of conidium formation | IMP PMID:16387865 FluG-dependent asexual development in Aspergillus nidulans o... | NEW | Summary: Proposed new annotation. The characterized role of SfgA - the one thing GOA does not capture - is repression of conidiation; deletion and 31 other loss-of-function sfgA alleles bypass the requirement for fluG in conidiation, and sfgA overexpression inhibits it. Reason: GOA holds only electronic, generic zinc-cluster transcription-factor terms for SfgA. This IMP-supported directional process term is the term the primary literature establishes, and it is already used for the other conidiation repressors in this module (velB, sfaD). Supporting Evidence: PMID:16387865 Deletion (Ξ) and 31 other loss-of-function sfgA mutations bypassed the need for fluG in conidiation and production of ST. PMID:16387865 In accordance with the proposed regulatory role of SfgA, overexpression of sfgA inhibited conidiation and delayed/reduced expression of conidiation- and ST-specific genes. |
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Download this section (compressed HTML)UniProt Q3I5F3 (SfgA). Zn(II)2Cys6 (zinc-cluster) transcription factor; negative
regulator of conidiation. Repressive input of the upstream-activation tier.
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