fluG encodes a cytoplasmic protein related to prokaryotic glutamine synthetase I (GSI) that is the upstream-most activator of asexual sporulation (conidiation) in Aspergillus nidulans. FluG is required for the production/accumulation of a small extracellular developmental signal; fluG-null strains fail to conidiate and grow as undifferentiated 'fluffy' colonies. Signalling from FluG relieves repression by SfgA and thereby permits induction of the Flb factors and the master regulator brlA. Although FluG belongs to the glutamine synthetase family, its role is signal biosynthesis; a classical in vivo glutamine synthetase activity has been experimentally excluded rather than merely left undemonstrated (A. nidulans glutamine synthesis is provided by GlnA). FluG also influences secondary metabolism (sterigmatocystin).
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0003824 catalytic activity | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: Generic catalytic-activity term (uninformative). Reason: Root-level electronic MF; FluG's activity is GSI-related, so this term adds no specific information. |
| GO:0005737 cytoplasm | IEA GO_REF:0000044 | ACCEPT | Summary: Accept: cytoplasm. Reason: Consistent with FluG's role as the upstream-most activator of conidiation (extracellular signal production). |
| GO:0016787 hydrolase activity | IEA GO_REF:0000002 | MARK AS OVER ANNOTATED | Summary: Likely incorrect MF: FluG is GSI-related (a ligase), not a hydrolase. Reason: FluG belongs to the glutamine synthetase family (ligase, EC 6.3.1.-); the electronic 'hydrolase activity' mapping is inconsistent with this and is likely an incorrect InterPro2GO assignment. |
| GO:0010913 regulation of sterigmatocystin biosynthetic process | IMP PMID:9305634 Aspergillus sporulation and mycotoxin production both requir... | KEEP AS NON CORE | Summary: Non-core regulatory role in sterigmatocystin biosynthesis. Reason: FluG affects ST biosynthesis as an upstream regulator; a pleiotropic, non-core role. |
| 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. 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: FluG regulates ST, it is not part of the biosynthetic pathway. Reason: FluG influences sterigmatocystin only as an upstream regulator; captured precisely by GO:0010913/GO:0010914. Proposed replacements: positive regulation of sterigmatocystin biosynthetic process |
| GO:0048315 conidium formation | IMP PMID:7926755 The Aspergillus nidulans fluG gene is required for productio... | ACCEPT | Summary: Core process. FluG is required for conidium formation. Reason: fluG-null strains are aconidial (fluffy); FluG is essential for the induction of conidiation. Supporting Evidence: PMID:7926755 Mutations in the Aspergillus nidulans fluG gene disrupt the programmed induction of asexual sporulation and result in formation of fluffy colonies that are characterized by undifferentiated cotton-like masses of vegetative cells. PMID:7926755 We show that the fluG mutant phenotype is suppressed when fluG mutant colonies are grown next to wild-type colonies even if the two strains are separated by dialysis membrane with a 6000- to 8000-dalton pore size. |
| 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: Broader parent of the ST-regulation role; non-core. |
| GO:0000905 sporocarp development involved in asexual reproduction | IMP PMID:1508186 Isolation of a gene required for programmed initiation of de... | ACCEPT | Summary: Core process. FluG is required for conidiophore (asexual sporocarp) development. Reason: FluG is required for development of the conidiophore, the asexual reproductive structure. |
| GO:0001896 autolysis | IMP PMID:19486415 Asexual sporulation signalling regulates autolysis of Asperg... | KEEP AS NON CORE | Summary: Non-core downstream effect on autolysis. Reason: Asexual-sporulation signalling (including fluG) modulates autolysis; downstream/non-core. |
| GO:0005737 cytoplasm | IDA PMID:7926755 The Aspergillus nidulans fluG gene is required for productio... | ACCEPT | Summary: Accept: cytoplasm. Reason: Consistent with FluG's role as the upstream-most activator of conidiation (extracellular signal production). |
| GO:0004356 glutamine synthetase activity | IMP NOT PMID:7926755 The Aspergillus nidulans fluG gene is required for productio... | ACCEPT | Summary: NOT annotation. FluG does NOT have glutamine synthetase activity: despite belonging to the GS family and carrying a GS-like domain required for signal production, the mutant analysis EXCLUDED a physiological glutamine synthetase activity rather than leaving it undemonstrated. Reason: A well-supported experimental negative, and the annotation should be read as such. The AspGD row is NOT|enables (IMP, PMID:7926755): fluG mutants are not glutamine auxotrophs and the GS-family similarity does not translate into the canonical activity. Accepting the negation is the correct action - KEEP_AS_NON_CORE would imply retaining a weak positive claim, which inverts what the annotation asserts. FluG's GS-like domain instead synthesises a distinct small diffusible developmental signal. Supporting Evidence: PMID:7926755 We consider it unlikely that FluG functions in synthesis of glutamine but instead propose that FluG functions as a GSI-related enzyme in synthesizing an extracellular signal directing asexual sporulation |
| GO:0075307 positive regulation of conidium formation | IMP PMID:7926755 The Aspergillus nidulans fluG gene is required for productio... | ACCEPT | Summary: Core process. FluG positively regulates conidium formation. Reason: As the upstream-most activator, FluG is a positive regulator of conidiation. Supporting Evidence: PMID:7926755 Mutations in the Aspergillus nidulans fluG gene disrupt the programmed induction of asexual sporulation and result in formation of fluffy colonies that are characterized by undifferentiated cotton-like masses of vegetative cells. PMID:7926755 We show that the fluG mutant phenotype is suppressed when fluG mutant colonies are grown next to wild-type colonies even if the two strains are separated by dialysis membrane with a 6000- to 8000-dalton pore size. |
| GO:0075307 positive regulation of conidium formation | IGI PMID:7926755 The Aspergillus nidulans fluG gene is required for productio... | ACCEPT | Summary: Core process. FluG positively regulates conidium formation (genetic interaction). Reason: Genetic-interaction evidence consistent with FluG as a positive regulator of conidiation. |
| GO:1901704 L-glutamine biosynthetic process | IMP NOT PMID:7926755 The Aspergillus nidulans fluG gene is required for productio... | ACCEPT | Summary: NOT annotation. FluG is NOT involved in L-glutamine biosynthesis - the process counterpart of the excluded glutamine synthetase activity above. Reason: Same experimental negative as GO:0004356, on the process side. The AspGD row is NOT|acts_upstream_of_or_within (IMP, PMID:7926755). Accepting the negation records what was ruled out; KEEP_AS_NON_CORE would misread the annotation as a retained weak positive. Supporting Evidence: PMID:7926755 We consider it unlikely that FluG functions in synthesis of glutamine but instead propose that FluG functions as a GSI-related enzyme in synthesizing an extracellular signal directing asexual sporulation |
Loading supporting content…
Download this section (compressed HTML)Loading supporting content…
Download this section (compressed HTML)Loading supporting content…
Download this section (compressed HTML)