flbA encodes a Regulator of G-protein Signaling (RGS) domain protein that antagonizes FadA (G-alpha) signaling in Aspergillus nidulans, stimulating GTP hydrolysis to switch off proliferation signaling and thereby license asexual sporulation. flbA loss gives fluffy, aconidial colonies with low brlA; flbA overexpression activates brlA and premature development. FlbA also positively influences sterigmatocystin biosynthesis.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005096 GTPase activator activity | IBA GO_REF:0000033 | ACCEPT | Summary: Accept: GTPase activator activity. Reason: The defining molecular function of an RGS-domain protein: FlbA accelerates GTP hydrolysis on FadA, returning it to the inactive GDP state. This is FlbA's core function, and the reason loss of flbA gives an aconidial, proliferative phenotype. |
| GO:0009898 cytoplasmic side of plasma membrane | IBA GO_REF:0000033 | ACCEPT | Summary: Accept: cytoplasmic side of plasma membrane. Reason: RGS proteins act where their G-alpha target is, at the inner leaflet of the plasma membrane. The location is appropriately specific and biologically expected, though it is not directly imaged in the studies cited here. |
| GO:0045744 negative regulation of G protein-coupled receptor signaling pathway | IBA GO_REF:0000033 | ACCEPT | Summary: Accept: negative regulation of G protein-coupled receptor signaling pathway. Reason: Signed and pathway-specific: FlbA antagonises FadA signalling, and that antagonism is what licenses conidiation. The most informative process term in this set. |
| GO:0035556 intracellular signal transduction | IEA GO_REF:0000002 | ACCEPT | Summary: Accept: intracellular signal transduction. Reason: General parent term. Correct, but far less informative than the negative-regulation-of-GPCR-signalling call above. |
| GO:0010914 positive regulation of sterigmatocystin biosynthetic process | IMP PMID:9305634 Aspergillus sporulation and mycotoxin production both requir... | KEEP AS NON CORE | Summary: Non-core positive regulation of ST biosynthesis. Reason: FlbA influences ST via its effect on G-protein signaling; non-core. |
| GO:0010914 positive regulation of sterigmatocystin biosynthetic process | IMP PMID:9339347 Dominant mutations affecting both sporulation and sterigmato... | KEEP AS NON CORE | Summary: Non-core positive regulation of ST biosynthesis (duplicate). Reason: Pleiotropic secondary-metabolism regulatory role. |
| GO:0045461 sterigmatocystin biosynthetic process | IMP PMID:9305634 Aspergillus sporulation and mycotoxin production both requir... | MARK AS OVER ANNOTATED | Summary: Over-annotated: regulator of sterigmatocystin, not part of the biosynthetic pathway. Reason: This subunit influences sterigmatocystin only via G-protein signaling (regulatory); the biosynthetic-process annotation overstates the role. The regulation term is more accurate. Proposed replacements: regulation of sterigmatocystin biosynthetic process |
| GO:0045574 sterigmatocystin catabolic process | IMP PMID:9339347 Dominant mutations affecting both sporulation and sterigmato... | UNDECIDED | Summary: Unresolved: an experimental AspGD row placing FlbA upstream of sterigmatocystin catabolism, which sits oddly beside its positive effect on ST production. Reason: FlbA's characterised effect on sterigmatocystin is positive (GO:0010914), so a role upstream of ST catabolism is unexpected. However, this is an experimental (IMP) annotation and only the abstract of PMID:9339347 is cached; the abstract reports that dominant fluffy mutants fail to produce sterigmatocystin but does not show what the curator read in the full text. Without the full text the row can be neither confirmed nor rejected, so it is left undecided rather than overruled. Supporting Evidence: PMID:9339347 we have found that 19 of these mutants are not only developmentally altered but also fail to produce the toxic, carcinogenic, secondary metabolite sterigmatocystin |
| GO:0048315 conidium formation | IMP PMID:7830576 Overexpression of flbA, an early regulator of Aspergillus as... | ACCEPT | Summary: Core process. FlbA is required for conidium formation. Reason: flbA-null strains are aconidial (fluffy, low brlA); FlbA is required for conidiation. Supporting Evidence: PMID:8895563 flbA encodes an Aspergillus nidulans RGS (regulator of G protein signaling) domain protein that is required for control of mycelial proliferation and activation of asexual sporulation |
| GO:1900376 regulation of secondary metabolite biosynthetic process | IMP PMID:9339347 Dominant mutations affecting both sporulation and sterigmato... | KEEP AS NON CORE | Summary: Non-core secondary-metabolite regulatory role. Reason: Regulatory reach over secondary metabolism; non-core. |
| GO:0006357 regulation of transcription by RNA polymerase II | IMP PMID:21624998 Regulation of conidiation by light in Aspergillus nidulans. | KEEP AS NON CORE | Summary: Indirect effect on transcription (via signaling). Reason: FlbA is an RGS protein, not a transcription factor; its effect on brlA transcription is indirect (relieving G-protein repression). Kept non-core. |
| GO:0035556 intracellular signal transduction | IMP PMID:7830576 Overexpression of flbA, an early regulator of Aspergillus as... | ACCEPT | Summary: Accept: intracellular signal transduction. Reason: flbA overexpression activates brlA and sporulation, which is a signalling readout. The term is general, but the mutational evidence that FlbA acts within a signalling pathway is genuine. |
| GO:0030436 asexual sporulation | IMP PMID:9305634 Aspergillus sporulation and mycotoxin production both requir... | ACCEPT | Summary: Core process. FlbA is required for asexual sporulation. Reason: FlbA attenuation of FadA signaling is required for asexual sporulation. Supporting Evidence: PMID:7830576 We have identified a gene called flbA (for fluffy low brlA expression) that is required for initiation of A. nidulans conidiophore development. PMID:7830576 Overexpression of flbA using an inducible promoter resulted in misscheduled expression of brlA in vegetative cells and caused hyphal tips to differentiate into spore-producing structures. |
| GO:0075306 regulation of conidium formation | IMP PMID:7830576 Overexpression of flbA, an early regulator of Aspergillus as... | ACCEPT | Summary: Core process. FlbA regulates conidium formation. Reason: FlbA controls the timing/onset of conidiation by antagonizing G-protein proliferation signaling. Supporting Evidence: PMID:8895563 flbA encodes an Aspergillus nidulans RGS (regulator of G protein signaling) domain protein that is required for control of mycelial proliferation and activation of asexual sporulation. |
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