gpgA

UniProt ID: Q5B9N8
Organism: Emericella nidulans (strain FGSC A4 / ATCC 38163 / CBS 112.46 / NRRL 194 / M139)
Review Status: DRAFT
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Gene Description

gpgA encodes the gamma subunit of the heterotrimeric G protein of Aspergillus nidulans. As part of the FadA(alpha)-SfaD(beta)-GpgA(gamma) complex, GpgA governs vegetative growth and development: it is required for normal growth and proper conidiation and influences sterigmatocystin production and sexual development.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0007186 G protein-coupled receptor signaling pathway
IBA
GO_REF:0000033
ACCEPT
Summary: Accept: G protein-coupled receptor signaling pathway.
Reason: G-gamma subunits transduce receptor input as part of the obligate G-beta-gamma dimer, so the pathway term is the correct family-level process for GpgA.
GO:0005834 heterotrimeric G-protein complex
IBA
GO_REF:0000033
ACCEPT
Summary: Accept: heterotrimeric G-protein complex.
Reason: Complex membership is the primary structural fact about a G-gamma subunit: GpgA partners SfaD (G-beta) and FadA (G-alpha), both annotated to the same complex.
GO:0007186 G protein-coupled receptor signaling pathway
IEA
GO_REF:0000002
ACCEPT
Summary: Accept: G protein-coupled receptor signaling pathway.
Reason: Sequence-similarity route to the same pathway term as the IBA row. Redundant, but not incorrect.
GO:0016020 membrane
IEA
GO_REF:0000044
ACCEPT
Summary: Accept: membrane.
Reason: G-gamma subunits are prenylated and membrane-anchored, which is how they tether G-beta-gamma to the inner leaflet. The term is very general, but the membrane association is a real structural feature.
GO:0031681 G-protein beta-subunit binding
IEA
GO_REF:0000002
ACCEPT
Summary: Accept: G-protein beta-subunit binding.
Reason: The G-gamma/G-beta interaction is obligate - G-gamma is only stable within the dimer - which makes this the most informative molecular function available for GpgA.
GO:0048315 conidium formation
IMP
PMID:15944346
Multiple roles of a heterotrimeric G-protein gamma-subunit i...
ACCEPT
Summary: Core process. GpgA regulates conidium formation.
Reason: GpgA (Ggamma) is required for proper conidiation as part of the G-protein complex.
Supporting Evidence:
PMID:15944346
Deletion (Ξ”) of gpgA resulted in restricted vegetative growth and lowered asexual sporulation.
GO:0010914 positive regulation of sterigmatocystin biosynthetic process
IMP
PMID:16467480
The phosducin-like protein PhnA is required for Gbetagamma-m...
KEEP AS NON CORE
Summary: Non-core role in ST biosynthesis regulation.
Reason: Promotes ST via G-protein signaling; non-core.
GO:0045461 sterigmatocystin biosynthetic process
IMP
PMID:16467480
The phosducin-like protein PhnA is required for Gbetagamma-m...
MARK AS OVER ANNOTATED
Summary: Over-annotated: GpgA regulates ST, it is not a biosynthetic enzyme.
Reason: GpgA is a Ggamma signaling subunit; the regulation term is accurate.
GO:1900378 positive regulation of secondary metabolite biosynthetic process
IMP
PMID:16467480
The phosducin-like protein PhnA is required for Gbetagamma-m...
KEEP AS NON CORE
Summary: Non-core positive regulation of secondary metabolism.
Reason: Regulatory reach; non-core.
GO:0000909 sporocarp development involved in sexual reproduction
IMP
PMID:15944346
Multiple roles of a heterotrimeric G-protein gamma-subunit i...
KEEP AS NON CORE
Summary: Non-core role in sexual (sporocarp) development.
Reason: GpgA also influences sexual development; non-core.
Supporting Evidence:
PMID:15944346
the Ξ” gpgA mutant was unable to produce sexual fruiting bodies (cleistothecia) in self-fertilization and was severely impaired with cleistothecial development in outcross, indicating that both SfaD and GpgA are required for fruiting body formation
GO:0005834 heterotrimeric G-protein complex
ISS
PMID:15944346
Multiple roles of a heterotrimeric G-protein gamma-subunit i...
ACCEPT
Summary: Accept: heterotrimeric G-protein complex.
Reason: Sequence-similarity assignment made in the paper characterising GpgA's roles in growth and development; concordant with the IBA row and with SfaD and FadA being annotated to the same heterotrimer.
Supporting Evidence:
PMID:15944346
strongly support the hypothesis that FadA, SfaD, and GpgA constitute a functional heterotrimeric unit, of which the primary role is to mediate vegetative growth signaling
GO:0075306 regulation of conidium formation
IMP
PMID:15944346
Multiple roles of a heterotrimeric G-protein gamma-subunit i...
ACCEPT
Summary: Core process. GpgA regulates conidium formation.
Reason: GpgA governs conidiation as part of the growth/development G-protein switch. The unsigned term is retained deliberately rather than signed to GO:0075308 as on its FadA and SfaD partners, because the gpgA loss-of-function phenotype runs the other way. Deleting sfaD gives hyperactive sporulation, whereas deleting gpgA lowers conidiation and, explicitly unlike the sfaD deletion, does not produce conidiophores in submerged culture, so GpgA cannot be called a negative regulator on this evidence. The reduced conidiation is in turn confounded by the restricted vegetative growth of the same mutant, so GO:0075307 is not assertable either, leaving the unsigned parent as the most specific defensible term.
Supporting Evidence:
PMID:15944346
unlike Ξ” sfaD , deletion of gpgA resulted in fluffy-reduced conidiation phenotypes during the early phase of growth and did not cause conidiophore formation in liquid submerged culture

Core Functions

Gamma subunit of the heterotrimeric G protein: GpgA acts in the FadA-SfaD-GpgA complex to govern vegetative growth and regulate conidiation, and modulates secondary metabolism and sexual development.

Supporting Evidence:
  • PMID:15944346
    strongly support the hypothesis that FadA, SfaD, and GpgA constitute a functional heterotrimeric unit, of which the primary role is to mediate vegetative growth signaling
  • PMID:15944346
    We propose that GpgA is the only A. nidulans GΞ³-subunit and is required for normal vegetative growth as well as proper asexual and sexual developmental progression.

References

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Notes

(gpgA-notes.md)

gpgA (Aspergillus nidulans) β€” curation notes

UniProt Q5B9N8 (GpgA). G-gamma subunit; repressive gating tier.
- Ggamma subunit governing growth and development. PMID:15944346.
- Core: regulation of conidium formation (GO:0075306). GO:0045461 ST biosynthetic process flagged over-annotation β†’ GO:0010914.

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