PufA is a Pumilio/FBF (PUF) family sequence-specific RNA-binding protein of Dictyostelium discoideum that acts as a translational repressor. Its C-terminal Pumilio homology domain (PUM-HD), built from eight tandem Pumilio repeats, binds a recognition element in the mRNA encoding the catalytic subunit of cAMP-dependent protein kinase (PKA-C, pkaC) and represses its translation in the cytoplasm. During vegetative growth PufA keeps PKA-C levels low; upon nutrient depletion the YakA kinase pathway drives the decline of PufA protein and mRNA, relieving repression so that PKA-C accumulates and triggers the growth-to-development transition, aggregation, and progression toward fruiting body (sorocarp) formation. PufA thereby couples nutritional status to the developmental program through post-transcriptional control of PKA-C synthesis.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0010608 post-transcriptional regulation of gene expression | IBA GO_REF:0000033 | ACCEPT | Summary: PufA is a PUF-family translational regulator that represses PKA-C mRNA translation, a canonical form of post-transcriptional regulation of gene expression. The phylogenetic inference is consistent with direct experimental evidence for this gene. Reason: This term accurately captures PufA's role as a sequence-specific mRNA binding translational repressor, supported both by the PUF family assignment and by direct experimental evidence that PufA controls PKA-C synthesis. The more specific child term negative regulation of translation is also annotated. Supporting Evidence: PMID:10375515 PufA is a translational regulator that directly controls PKA-C synthesis |
| GO:0005737 cytoplasm | IBA GO_REF:0000033 | ACCEPT | Summary: PUF-family translational repressors act in the cytoplasm, where translation occurs. This localization is consistent with PufA's function as a cytoplasmic translational regulator of PKA-C mRNA and with the UniProt subcellular location assignment. Reason: Cytoplasmic activity is expected for a translational repressor and is consistent both with phylogenetic inference from the PUF family and the UniProt subcellular-location mapping. This represents the compartment in which the core molecular function is exercised. |
| GO:0003730 mRNA 3'-UTR binding | IBA GO_REF:0000033 | ACCEPT | Summary: PUF proteins characteristically recognize sequence elements in the 3'-UTR of target mRNAs through their Pumilio homology domain. PufA binds a recognition element in the PKA-C mRNA, and this term is the most informative molecular-function descriptor of that sequence-specific binding activity. Reason: The PUM-HD domain of PufA (eight Pumilio repeats) mediates sequence-specific mRNA recognition, the defining molecular function of the family. Direct experimental evidence shows PufA forms a complex with a segment of PKA-C mRNA, and 3'-UTR recognition is the canonical PUF binding mode, making this the preferred informative MF term. Supporting Evidence: PMID:10375515 Gel mobility-shift assays using a 200-base segment of PKA-C's mRNA as a probe reveals a complex with wild-type cell extracts, but not with pufA- cell extracts |
| GO:0003723 RNA binding | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro2GO annotation from the Pumilio/PUF RNA-binding domain signatures. This is correct but general; the more specific terms mRNA binding and mRNA 3'-UTR binding better describe PufA's actual sequence-specific activity. Reason: The RNA-binding assignment is correct and consistent with the PUM-HD domain architecture, but it is a broad parent term. It is retained as an accurate general annotation subsumed by the more specific mRNA-binding terms. |
| GO:0005737 cytoplasm | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt subcellular-location mapping places PufA in the cytoplasm, consistent with its role as a cytoplasmic translational repressor. Reason: Cytoplasmic localization is appropriate for a PUF-family translational regulator and is consistent with the phylogenetic (IBA) cytoplasm annotation. |
| GO:0003729 mRNA binding | IMP PMID:10375515 Starvation promotes Dictyostelium development by relieving P... | ACCEPT | Summary: Direct experimental evidence (gel mobility-shift) shows that PufA forms a complex with a segment of PKA-C mRNA, present in wild-type but not pufA-null extracts. This is a well-supported core molecular function. Reason: Gel mobility-shift assays demonstrate sequence-specific binding of PufA to PKA-C mRNA, and this activity is lost in pufA-null cells, providing direct genetic and biochemical support for the mRNA-binding function. Supporting Evidence: PMID:10375515 Gel mobility-shift assays using a 200-base segment of PKA-C's mRNA as a probe reveals a complex with wild-type cell extracts, but not with pufA- cell extracts |
| GO:0005575 cellular_component | ND GO_REF:0000015 | ACCEPT | Summary: Root cellular component ND annotation: when it was made, no cellular component had been curated for this gene product from literature. Reason: ACCEPT under the ND acceptance rule (projects/NO_DATA.md). The evidence this review cites for the cellular component is inferred (from orthologs, family membership or sequence features) or comes from other species; none of it is literature on this gene product in this species. This was judged from the review's own content during the NO_DATA re-action pass, not from a new literature search. Earlier action: REMOVE. Re-checked 2026-10-31: PMID:10375515, cited in core_functions, shows PufA translational regulation, not a localization. |
| GO:0017148 negative regulation of translation | IMP PMID:10375515 Starvation promotes Dictyostelium development by relieving P... | ACCEPT | Summary: PufA represses translation of the PKA-C mRNA; loss of PufA leads to PKA-C overexpression. This is a core biological process directly demonstrated by mutant analysis. Reason: PufA acts as a translational inhibitor of PKA-C, and pufA-null cells overexpress PKA-C, providing direct experimental support for negative regulation of translation as a core function. Supporting Evidence: PMID:10375515 Upon starvation, pufA- cells develop precociously and overexpress developmentally important proteins, including the catalytic subunit of cAMP-dependent protein kinase, PKA-C |
| GO:0030587 sorocarp development | IMP PMID:10375515 Starvation promotes Dictyostelium development by relieving P... | KEEP AS NON CORE | Summary: PufA regulates the timing of the developmental program, and its downregulation by the YakA pathway de-represses PKA-C and triggers aggregation and fruiting body (sorocarp) development. pufA-null cells develop precociously. This is an upstream regulatory role rather than the core molecular function. Reason: PufA influences sorocarp development indirectly by controlling PKA-C translation at the growth-to-development transition. The acts_upstream_of_or_within qualifier is appropriate, but developmental progression is a downstream consequence of PufA's translational repressor activity, so this is best retained as a non-core process annotation. Supporting Evidence: PMID:10375515 Upon starvation, pufA- cells develop precociously and overexpress developmentally important proteins, including the catalytic subunit of cAMP-dependent protein kinase, PKA-C PMID:10375515 YakA regulates the initiation of development by inhibiting the expression of PufA |
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