vosA ("viability of spores A") is a velvet-family regulatory protein that governs spore maturation and dormancy in Aspergillus nidulans. Expressed specifically during formation of both asexual (conidia) and sexual (ascospores) spores, VosA couples sporogenesis to trehalose biogenesis and, together with VelB, forms an NF-kB-like DNA-binding regulatory complex that represses cell-wall (beta-glucan) biosynthetic genes in spores and confers spore viability, trehalose accumulation and long-term stress resistance. VosA also feeds back to restrain premature germination and asexual development.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005634 nucleus | IBA GO_REF:0000033 | ACCEPT | Summary: Nuclear velvet regulator. Reason: VosA is a nuclear DNA-binding regulatory protein; consistent with IDA nucleus annotations. |
| GO:0005992 trehalose biosynthetic process | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: VosA regulates trehalose biogenesis in spores (regulatory, not enzymatic). Reason: VosA couples sporogenesis to trehalose biosynthesis by regulating trehalose-pathway genes; it is a regulator, not a biosynthetic enzyme, so this is a non-core regulatory role. Supporting Evidence: PMID:17912349 we identify the novel regulator VosA that couples the formation of spores and focal trehalose biogenesis in the model fungus Aspergillus nidulans |
| GO:0030435 sporulation resulting in formation of a cellular spore | IBA GO_REF:0000033 | ACCEPT | Summary: Core process. VosA functions in cellular-spore formation/maturation. Reason: VosA is required for proper spore maturation and viability of both conidia and ascospores. |
| GO:0005634 nucleus | IEA GO_REF:0000044 | ACCEPT | Summary: Nuclear localization (UniProt mapping). Reason: Consistent with the experimentally determined nuclear localization. |
| GO:0005515 protein binding | IPI PMID:24391470 The velvet family of fungal regulators contains a DNA-bindin... | MODIFY | Summary: Protein binding (uninformative MF) reflecting the VosA-VelB velvet-domain heterodimer, solved crystallographically in this study. Reason: The IPI rests on the VosA-VelB heterodimer whose crystal structure was determined in this paper; protein heterodimerization activity (GO:0046982) captures the informative content of the interaction. The homodimer is separately covered by the identical protein binding row. Proposed replacements: protein heterodimerization activity Supporting Evidence: PMID:24391470 In order to unveil the molecular basis of the VosA-VelB interaction, we also determined the crystal structure of the VosA1β190-VelB heterodimer |
| GO:0042802 identical protein binding | IPI PMID:24391470 The velvet family of fungal regulators contains a DNA-bindin... | KEEP AS NON CORE | Summary: Identical protein binding (velvet dimerization). Reason: Reflects velvet-family homo/hetero-dimerization; retained as non-core supporting evidence for complex formation. |
| GO:0048315 conidium formation | IMP PMID:25960370 Velvet-mediated repression of Ξ²-glucan synthesis in Aspergil... | ACCEPT | Summary: Core process. VosA regulates conidium formation/maturation. Reason: VosA (with VelB) represses spore cell-wall biosynthetic genes and is required for proper conidial maturation. Supporting Evidence: PMID:25960370 turned off by the NF-kB like fungal regulators VosA and VelB in Aspergillus nidulans |
| GO:0005634 nucleus | IDA PMID:21152013 LaeA control of velvet family regulatory proteins for light-... | ACCEPT | Summary: Nuclear localization (direct). Reason: Direct assay places VosA in the nucleus, consistent with its DNA-binding regulatory role. Supporting Evidence: PMID:21152013 Whereas VelB can form homodimers in both cytoplasm and nucleus, VosA-VelB is preferentially located in the nucleus. |
| GO:0005992 trehalose biosynthetic process | IMP PMID:21152013 LaeA control of velvet family regulatory proteins for light-... | KEEP AS NON CORE | Summary: VosA regulates trehalose biosynthesis (direct, regulatory). Reason: Direct genetic evidence that VosA controls trehalose biogenesis; a regulatory rather than enzymatic role. Supporting Evidence: PMID:17912349 The vosA gene is expressed specifically during the formation of both sexual and asexual spores (conidia) |
| GO:0005634 nucleus | IDA PMID:17912349 A novel regulator couples sporogenesis and trehalose biogene... | ACCEPT | Summary: Nuclear localization (direct). Reason: Direct assay; consistent with the founding VosA characterization. Supporting Evidence: PMID:17912349 At 48 h, when all conidia become mature, VosA-RFP localizes mainly in the nucleus of mature conidia |
| GO:0030435 sporulation resulting in formation of a cellular spore | IMP PMID:17912349 A novel regulator couples sporogenesis and trehalose biogene... | ACCEPT | Summary: Core process. VosA governs cellular-spore formation. Reason: Gain-of-function and deletion analyses establish VosA as a regulator of spore formation and viability. Supporting Evidence: PMID:17912349 we identify the novel regulator VosA that couples the formation of spores and focal trehalose biogenesis in the model fungus Aspergillus nidulans |
| GO:0048315 conidium formation | IMP PMID:17912349 A novel regulator couples sporogenesis and trehalose biogene... | ACCEPT | Summary: Core process. VosA is required for conidium formation/maturation. Reason: VosA is expressed during conidiogenesis and required for conidial maturation and viability. Supporting Evidence: PMID:17912349 The vosA gene is expressed specifically during the formation of both sexual and asexual spores (conidia) |
| GO:0000981 DNA-binding transcription factor activity, RNA polymerase II-specific | IDA PMID:24391470 The velvet family of fungal regulators contains a DNA-bindin... | NEW | Summary: VosA binds a defined promoter motif (CTGGCCaaGGC) in target-gene promoters such as brlA, and its loss alters expression of those targets. Reason: ChIP-chip, motif discovery and EMSA (including binding-site deletion and DNA-contact mutants) show sequence-specific DNA binding by the VosA velvet domain, and vosA deletion changes transcript levels of the bound target genes. This supports the core MF already asserted in core_functions, which otherwise has no supporting annotation row. The characterised targets (brlA, nsdD, cteA and others) are protein-coding RNA polymerase II genes, so the Pol II-specific term is used. Supporting Evidence: PMID:24391470 The DNA binding activity of the mutated VosA1β190 proteins was tested by an EMSA with the 35 bp fragment of the brlAΞ² promoter containing the VosA binding motifs (Figure 4) and additionally with the same brlAΞ² promoter fragment with deleted VosA binding motifs 1 and 2 (Figure S10), verifying the importance of both motifs in VosA-DNA interaction. PMID:24391470 Deletion of velB, similar to deletion of vosA, caused reduced accumulation of AN8694, nsdD, AN5371, cteA, AN6508, and AN5709 mRNAs, but increased transcript levels of brlA, treA AN8741, and rfeG |
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