ALO1 encodes a FAD-dependent D-arabinono-1,4-lactone oxidase associated with the mitochondrial outer membrane. It catalyzes the terminal oxidation in yeast D-erythroascorbate biosynthesis and contributes to oxidative-stress resistance. Alo1 also binds the Myo2 cargo-binding domain and supports mitochondrial inheritance.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000001 mitochondrion inheritance | IGI PMID:39775849 A protein interaction map of the myosin Myo2 reveals a role ... | KEEP AS NON CORE | Summary: Alo1 supports bud-directed mitochondrial transport and inheritance in budding yeast. Reason: The 2025 Myo2 interactome study identified Alo1 as a robust Myo2-cargo domain hit, localized it to the mitochondrial outer membrane, and reported mitochondrial morphology and inheritance defects in cells lacking ALO1. SGD's IGI annotation is therefore consistent with Alo1 acting with the Myo2 transport system in mitochondrial inheritance, but this is a contextual outer-membrane transport role rather than Alo1's defining FAD-linked oxidase activity. Supporting Evidence: PMID:39775849 One robust hit was Alo1, a poorly characterized D-arabinono-1,4-lactone oxidase located in the mitochondrial outer membrane. We found that mutants lacking Alo1 exhibited defects in mitochondrial morphology and inheritance. |
| GO:0000001 mitochondrion inheritance | IMP PMID:39775849 A protein interaction map of the myosin Myo2 reveals a role ... | KEEP AS NON CORE | Summary: ALO1 loss perturbs mitochondrial morphology and inheritance. Reason: Loss-of-function evidence from the 2025 Myo2 interaction study supports ALO1 acting upstream of or within mitochondrial inheritance, probably by helping recruit the myosin V motor Myo2 to mitochondria. This is a real but secondary process annotation beside the core D-erythroascorbate biosynthetic activity. Supporting Evidence: PMID:39775849 One robust hit was Alo1, a poorly characterized D-arabinono-1,4-lactone oxidase located in the mitochondrial outer membrane. We found that mutants lacking Alo1 exhibited defects in mitochondrial morphology and inheritance. During oxidative stress, dysfunctional mitochondria are immobilized in the mother in wild-type cells. Intriguingly, overexpression of ALO1 restored bud-directed transport of mitochondria under these conditions. We propose that Alo1 supports the recruitment of Myo2 to mitochondria and its activity is particularly important under oxidative stress. |
| GO:0003885 D-arabinono-1,4-lactone oxidase activity | IBA GO_REF:0000033 | ACCEPT | Summary: The fungal PAINT node accurately transfers D-arabinono-1,4-lactone oxidase activity to budding yeast ALO1. Reason: Experimental S. cerevisiae evidence purified the D-arabinono-1,4-lactone oxidase from mitochondria and identified YML086C/ALO1 as the encoding gene. PAINT places this exact GO:0003885 function at the fungal PTHR43762:SF1 D-arabinono-1,4-lactone oxidase node PTN000356435, seeded by S. cerevisiae ALO1 and Candida albicans ALO1; ALO1 is a descendant of that node, so the IBA is well scoped. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN000356435 · PTN000356435 SUPPORTS TRANSFER The PTHR43762 PAINT cache places GO:0003885 at PTN000356435, the fungal SF1 clade containing budding-yeast and Candida ALO1 proteins. Supporting Evidence: PMID:10094636 D-Arabinono-1,4-lactone oxidase catalysing the final step of D-erythroascorbic acid biosynthesis was purified from the mitochondrial fraction of Saccharomyces cerevisiae. Based on the amino acid sequence analysis of the enzyme, an unknown open reading frame (ORF), YML086C, was identified as the ALO1 gene encoding the enzyme. |
| GO:0003885 D-arabinono-1,4-lactone oxidase activity | IDA PMID:10094636 D-Erythroascorbic acid is an important antioxidant molecule ... | ACCEPT | Summary: Purified mitochondrial Alo1 catalyzes D-arabinono-1,4-lactone oxidation. Reason: The SGD IDA annotation is direct experimental evidence from the paper that purified the enzyme from the mitochondrial fraction, matched peptide sequence to YML086C, and showed that alo1 mutants lose D-arabinono-1,4-lactone oxidase activity. Supporting Evidence: PMID:10094636 In the alo1 mutants, D-erythroascorbic acid and the activity of D-arabinono-1,4-lactone oxidase could not be detected. |
| GO:0003885 D-arabinono-1,4-lactone oxidase activity | IEA GO_REF:0000120 | ACCEPT | Summary: The ARBA/InterPro/Rhea/EC mapping lands on the exact Alo1 catalytic activity. Reason: UniProt and InterPro classify ALO1 as a sugar-lactone oxidase in the ALO_C family, and Rhea:23756/EC:1.1.3.37 correspond to oxidation of D-arabinono-1,4-lactone to dehydro-D-arabinono-1,4-lactone. This electronic assertion is corroborated by direct biochemical evidence for the same activity in S. cerevisiae. Supporting Evidence: PMID:10094636 D-Arabinono-1,4-lactone oxidase catalysing the final step of D-erythroascorbic acid biosynthesis was purified from the mitochondrial fraction of Saccharomyces cerevisiae. |
| GO:0003885 D-arabinono-1,4-lactone oxidase activity | RCA GO_REF:0000123 | ACCEPT | Summary: The YeastPathways conversion assigns the correct ALO1 enzyme activity. Reason: ALO1 catalyzes the final D-erythroascorbate biosynthesis reaction, so the pathway-derived RCA row recovers the same D-arabinono-1,4-lactone oxidase activity supported by the original biochemical characterization. Supporting Evidence: PMID:10094636 D-Arabinono-1,4-lactone oxidase catalysing the final step of D-erythroascorbic acid biosynthesis was purified from the mitochondrial fraction of Saccharomyces cerevisiae. |
| GO:0005739 mitochondrion | HDA PMID:14576278 The proteome of Saccharomyces cerevisiae mitochondria. | KEEP AS NON CORE | Summary: ALO1 was recovered in a high-throughput purified-mitochondria proteome. Reason: SGD's HDA row comes from a broad mass-spectrometry survey of highly purified yeast mitochondria. Although the abstract does not name ALO1, this is curator-extracted proteomics evidence and agrees with both direct mitochondrial fractionation evidence and the later outer-membrane localization; the broad mitochondrion term is kept as supporting location evidence. Supporting Evidence: PMID:14576278 We performed a comprehensive approach to determine the proteome of Saccharomyces cerevisiae mitochondria. The proteins of highly pure yeast mitochondria were separated by several independent methods and analyzed by tandem MS. |
| GO:0005739 mitochondrion | HDA PMID:16823961 Toward the complete yeast mitochondrial proteome: multidimen... | KEEP AS NON CORE | Summary: ALO1 was recovered in the PROMITO high-throughput mitochondrial proteome. Reason: This HDA annotation is consistent with ALO1 being a mitochondrial outer membrane enzyme. The underlying PROMITO study is abstract-only in the cache, so the row is retained as secondary support rather than treated as independent low-level localization evidence. Supporting Evidence: PMID:16823961 A total of 851 different proteins (PROMITO dataset) were identified by use of multidimensional LC-MS/MS, 1D-SDS-PAGE combined with nano-LC-MS/MS and 2D-PAGE with subsequent MALDI-mass fingerprinting. |
| GO:0005739 mitochondrion | HDA PMID:24769239 Quantitative variations of the mitochondrial proteome and ph... | KEEP AS NON CORE | Summary: ALO1 was recovered in a high-throughput mitochondrial proteomics study across fermentative and respiratory growth conditions. Reason: This broad mitochondrion HDA row is compatible with the direct placement of Alo1 at the mitochondrial outer membrane. The cached abstract describes the isolated-mitochondria quantitative proteomic experiment but does not list individual proteins, so this row should remain secondary to the direct ALO1 localization evidence. Supporting Evidence: PMID:24769239 In this aim we performed an overall quantitative proteomic and phosphoproteomic study of isolated mitochondria extracted from yeast grown on fermentative (glucose or galactose) and respiratory (lactate) media. |
| GO:0005739 mitochondrion | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: The PAINT mitochondrion placement is biologically correct for fungal ALO1 enzymes but less specific than the outer-membrane evidence. Reason: PTN001015900 places mitochondrial activity on the fungal ALO1 clade, seeded by budding-yeast and Candida ALO1 annotations. That placement is valid and not weakened by the short seed list, while newer S. cerevisiae evidence refines the location to the cytoplasmic side of the mitochondrial outer membrane. Propagation Review Root cause: NO FAILURE NON CORE Sources checked: PANTHER:PTN001015900 · PTN001015900 SUPPORTS TRANSFER The PTHR43762 PAINT cache places the mitochondrial IBD on the fungal node PTN001015900, which contains S. cerevisiae ALO1 and is seeded by fungal ALO1 experimental annotations. Supporting Evidence: PMID:39775849 One robust hit was Alo1, a poorly characterized D-arabinono-1,4-lactone oxidase located in the mitochondrial outer membrane. |
| GO:0005739 mitochondrion | IDA PMID:10094636 D-Erythroascorbic acid is an important antioxidant molecule ... | KEEP AS NON CORE | Summary: Purified Alo1 activity was found in the mitochondrial fraction. Reason: The original biochemical purification directly supports a mitochondrial association for Alo1; later studies place the enzyme more precisely at the mitochondrial outer membrane, making this broad compartment correct but non-core. Supporting Evidence: PMID:10094636 D-Arabinono-1,4-lactone oxidase catalysing the final step of D-erythroascorbic acid biosynthesis was purified from the mitochondrial fraction of Saccharomyces cerevisiae. |
| GO:0005739 mitochondrion | IEA GO_REF:0000117 | KEEP AS NON CORE | Summary: ARBA assigns the correct broad mitochondrial location. Reason: The UniProt/ARBA electronic mitochondrion mapping is a true but broad parent of the more informative mitochondrial outer membrane and cytoplasmic-side location established for Alo1. Supporting Evidence: PMID:39775849 One robust hit was Alo1, a poorly characterized D-arabinono-1,4-lactone oxidase located in the mitochondrial outer membrane. |
| GO:0005741 mitochondrial outer membrane | HDA PMID:16407407 Proteomic analysis of the yeast mitochondrial outer membrane... | ACCEPT | Summary: Outer-membrane proteomics supports Alo1 at the mitochondrial outer membrane. Reason: The cached abstract describes a high-throughput proteome of purified yeast mitochondrial outer membranes but does not expose the ALO1-specific supplemental row; keep the annotation as SGD-curated outer-membrane proteomics evidence that agrees with the newer 2025 outer-membrane study. Supporting Evidence: PMID:16407407 we used a eukaryotic model organism, the yeast Saccharomyces cerevisiae, to determine the proteome of highly purified mitochondrial outer membranes. |
| GO:0005741 mitochondrial outer membrane | IDA PMID:16689936 Integral membrane proteins in the mitochondrial outer membra... | ACCEPT | Summary: Alo1 localizes to the mitochondrial outer membrane. Reason: SGD's IDA row is accepted by deference to SGD's full-text curation of the 2006 outer-membrane study. The local abstract does not name Alo1, but the newer Myo2 paper independently describes Alo1 as a mitochondrial outer-membrane protein. Supporting Evidence: PMID:39775849 One robust hit was Alo1, a poorly characterized D-arabinono-1,4-lactone oxidase located in the mitochondrial outer membrane. |
| GO:0005829 cytosol | RCA GO_REF:0000123 | REMOVE | Summary: The YeastPathways cytosol placement conflicts with Alo1 being embedded in the mitochondrial outer membrane. Reason: The pathway conversion likely modeled the soluble side of the reaction, but Alo1 itself is embedded in the mitochondrial outer membrane and is already represented by direct outer-membrane localization rows. Supporting Evidence: PMID:39775849 One robust hit was Alo1, a poorly characterized D-arabinono-1,4-lactone oxidase located in the mitochondrial outer membrane. |
| GO:0016020 membrane | IEA GO_REF:0000120 | TOO GENERAL | Summary: The UniProt/InterPro membrane prediction is true but very broad. Reason: ALO1 is a membrane-embedded mitochondrial outer-membrane enzyme, so a generic membrane annotation is not false, but it is a parent-level location beside more informative mitochondrial outer-membrane terms. Supporting Evidence: PMID:39775849 One robust hit was Alo1, a poorly characterized D-arabinono-1,4-lactone oxidase located in the mitochondrial outer membrane. |
| GO:0016491 oxidoreductase activity | IEA GO_REF:0000002 | MODIFY | Summary: The generic InterPro oxidoreductase row should be replaced by the exact D-arabinono-1,4-lactone oxidase activity. Reason: The InterPro active-site signature only supports a broad FAD-dependent oxidoreductase parent, whereas ALO1 has direct biochemical and orthology support for GO:0003885. Proposed replacements: D-arabinono-1,4-lactone oxidase activity Supporting Evidence: PMID:10094636 In the alo1 mutants, D-erythroascorbic acid and the activity of D-arabinono-1,4-lactone oxidase could not be detected. |
| GO:0016899 oxidoreductase activity, acting on the CH-OH group of donors, oxygen as acceptor | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: The ALO_C oxidoreductase parent is a valid umbrella for Alo1's lactone oxidase substrate range. Reason: GO:0016899 is a correct parent-level oxidoreductase class, but the physiological core term is GO:0003885 D-arabinono-1,4-lactone oxidase activity. UniProt records purified Alo1 activity on L-gulono-1,4-lactone and L-galactono-1,4-lactone as well as D-arabinono-1,4-lactone, so the broader oxygen-acceptor CH-OH oxidoreductase class is true in vitro rather than a propagation failure. Supporting Evidence: file:yeast/ALO1/ALO1-uniprot.txt Can oxidize L-gulono-1,4-lactone as well as D-arabinono-1,4-lactone and L-galactono-1,4-lactone. |
| GO:0031489 myosin V binding | IPI PMID:39775849 A protein interaction map of the myosin Myo2 reveals a role ... | KEEP AS NON CORE | Summary: Alo1 physically interacts with the cargo-binding domain of the myosin V motor Myo2. Reason: A genome-wide protein-fragment complementation screen identified Alo1 as a robust Myo2 cargo-binding-domain interactor, and the same study connected ALO1 to bud-directed mitochondrial inheritance. GO:0031489 is therefore an informative non-core molecular-function annotation for this nonenzymatic role. Supporting Evidence: PMID:39775849 To search for novel components involved in this process, we performed a protein fragment complementation screen using the cargo-binding domain of Myo2, the major organelle transporter in yeast, as bait and a genome-wide strain collection expressing yeast proteins as prey. One robust hit was Alo1 |
| GO:0031966 mitochondrial membrane | IEA GO_REF:0000044 | TOO GENERAL | Summary: The generic mitochondrial membrane row is true but less precise than Alo1's outer-membrane, cytoplasmic-side location. Reason: UniProt's SubCell mapping to mitochondrial membrane is directionally correct for membrane-embedded Alo1, but SGD now has direct evidence for the cytoplasmic side of the mitochondrial outer membrane, a more precise component for the same protein. Supporting Evidence: PMID:39775849 One robust hit was Alo1, a poorly characterized D-arabinono-1,4-lactone oxidase located in the mitochondrial outer membrane. |
| GO:0032473 cytoplasmic side of mitochondrial outer membrane | IDA PMID:39775849 A protein interaction map of the myosin Myo2 reveals a role ... | ACCEPT | Summary: Alo1 localizes to the cytoplasmic side of the mitochondrial outer membrane. Reason: SGD's direct 2025 annotation is accepted as the most specific current localization for Alo1. The cached abstract supports mitochondrial outer-membrane localization and the proposed Myo2 recruitment model but does not itself expose the cytoplasmic-side assay, so the exact side is retained by deference to SGD's full-text curation. Supporting Evidence: PMID:39775849 One robust hit was Alo1, a poorly characterized D-arabinono-1,4-lactone oxidase located in the mitochondrial outer membrane. |
| GO:0034599 cellular response to oxidative stress | IEA GO_REF:0000117 | KEEP AS NON CORE | Summary: ARBA's oxidative-stress process assertion is supported but broad. Reason: ALO1 is needed to produce the antioxidant D-erythroascorbate and affects oxidative-stress resistance, so the stress-response annotation is biologically consistent. The more exact core process is D-erythroascorbate biosynthesis. Supporting Evidence: PMID:10094636 The alo1 mutants showed increased sensitivity towards oxidative stress, but overexpression of ALO1 made the cells more resistant to oxidative stress. |
| GO:0034599 cellular response to oxidative stress | IMP PMID:10094636 D-Erythroascorbic acid is an important antioxidant molecule ... | KEEP AS NON CORE | Summary: ALO1 perturbation alters resistance to oxidative stress. Reason: Mutant and overexpression phenotypes show that ALO1 contributes to the cellular response to oxidative stress through D-erythroascorbate production, but this broader response term should be read as a physiological outcome of the more specific biosynthetic activity. Supporting Evidence: PMID:10094636 The alo1 mutants showed increased sensitivity towards oxidative stress, but overexpression of ALO1 made the cells more resistant to oxidative stress. |
| GO:0050660 flavin adenine dinucleotide binding | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: ALO1 contains the conserved FAD-binding region of sugar-lactone oxidases. Reason: FAD binding is mechanistically necessary for the covalent FAD-linked oxidase fold and agrees with ALO1's sequence features, but it is a cofactor binding term subordinate to the specific D-arabinono-1,4-lactone oxidase activity. Supporting Evidence: PMID:10094636 The deduced amino acid sequence of the enzyme shared 32% and 21% identity with that of L-gulono-1,4-lactone oxidase from rat and L-galactono-1,4-lactone dehydrogenase from cauliflower, respectively, and contained a putative transmembrane segment and a covalent FAD binding site. |
| GO:0070485 dehydro-D-arabinono-1,4-lactone biosynthetic process | IMP PMID:10094636 D-Erythroascorbic acid is an important antioxidant molecule ... | ACCEPT | Summary: ALO1 catalyzes the terminal step of D-erythroascorbate biosynthesis. Reason: The original alo1 deletion and multicopy-complementation evidence directly ties YML086C/ALO1 to the final oxidation in D-erythroascorbate biosynthesis. Supporting Evidence: PMID:10094636 In the alo1 mutants, D-erythroascorbic acid and the activity of D-arabinono-1,4-lactone oxidase could not be detected. The intracellular concentration of D-erythroascorbic acid and the enzyme activity increased up to 6.9-fold and 7.3-fold, respectively, in the transformant cells carrying ALO1 in multicopy plasmid. |
| GO:0070485 dehydro-D-arabinono-1,4-lactone biosynthetic process | RCA GO_REF:0000123 | ACCEPT | Summary: The YeastPathways conversion correctly places ALO1 in D-erythroascorbate biosynthesis. Reason: ALO1 is the enzyme for the final pathway reaction from D-arabinono-1,4-lactone to dehydro-D-arabinono-1,4-lactone, so the pathway-derived biological-process assertion is appropriate and matches the direct mutant phenotype. Supporting Evidence: PMID:10094636 D-Arabinono-1,4-lactone oxidase catalysing the final step of D-erythroascorbic acid biosynthesis was purified from the mitochondrial fraction of Saccharomyces cerevisiae. |
| GO:0071949 FAD binding | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: The PCMH-type domain supports FAD binding by Alo1. Reason: This FAD-binding annotation is true for a covalent FAD-linked lactone oxidase, but the cofactor term is less informative than the specific catalytic activity that FAD supports. Supporting Evidence: PMID:10094636 The deduced amino acid sequence of the enzyme shared 32% and 21% identity with that of L-gulono-1,4-lactone oxidase from rat and L-galactono-1,4-lactone dehydrogenase from cauliflower, respectively, and contained a putative transmembrane segment and a covalent FAD binding site. |
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Download this section (compressed HTML)Q: Does Alo1's oxidase activity directly modulate Myo2 recruitment to mitochondria, or does Alo1 provide a distinct outer-membrane interaction surface independent of D-erythroascorbate synthesis?
Experiment: Reconstitute Alo1 variants that abolish D-arabinono-1,4-lactone oxidase activity but preserve mitochondrial outer-membrane targeting, then assay Myo2 binding and bud-directed mitochondrial inheritance under oxidative stress.
D-Arabinono-1,4-lactone oxidase; catalyzes the final step in biosynthesis of dehydro-D-arabinono-1,4-lactone, which is protective against oxidative stress; putative adaptor protein that interacts with the cargo-binding domain of Myo2p and has a role in mitochondrial inheritance, especially under conditions of oxidative stress; localizes to the mitochondrial outer membrane; null mutant shows improved noncanonical amino acid incorporation efficiency in response to the amber (TAG) stop codon
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