SOT17 (AtSOT17, AtST5c, At1g18590) is a cytosolic PAPS-dependent sulfotransferase that catalyzes the final step of core glucosinolate structure formation, transferring a sulfate group from 3'-phosphoadenosine 5'-phosphosulfate to the thiohydroximate N-hydroxyl of desulfoglucosinolates to yield glucosinolates and adenosine 3',5'-bisphosphate. Together with its paralogs SOT16 (ST5a) and SOT18 (ST5b) it accepts a broad range of aromatic, indolic and aliphatic desulfoglucosinolates in vitro, but SOT17 shows increasing specific activity with increasing side-chain length of methionine-derived substrates, preferring long-chain methylthioalkyl desulfoglucosinolates such as 8-methylthiooctyl. It is expressed mainly in roots, stems and mature leaves and is inhibited by the reaction product PAP.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005634 nucleus | HDA PMID:28887381 Global Analysis of Membrane-associated Protein Oligomerizati... | MARK AS OVER ANNOTATED | Summary: The microsome experiment does not independently establish nucleus localization. Reason: Full-text inspection of PMID:28887381 shows that washed microsomes were profiled by chromatography and sucrose gradients, while subcellular labels were taken from SUBAcon and prior GFP data. The authors explicitly report that no organelle occupied a single gradient cluster. Detection or membrane association is meaningful, but assigning SOT17 specifically to nucleus exceeds the spatial resolution of this experiment. This is not a claim that the detected protein is absent or that all additional localization is impossible; the unsupported compartment assignment, rather than the proteomic observation, is marked as over-annotated. Supporting Evidence: PMID:16367753 All three desulfoglucosinolate AtSOT proteins are localized in the cytoplasm, as demonstrated by transient expression of fusion constructs with the green fluorescent protein in Arabidopsis protoplasts. PMID:28887381 Over 150 proteins had a complicated localization pattern, and were clearly partitioned between cytosolic and membrane-associated pools. PMID:28887381 The proteins with known localizations had scattered distributions across the entire gradient and no organelle fell in a single cluster. PMID:28887381 We used SUBAcon localization predictions to analyze oligomerization as a function of subcellular localization (Fig. 7C). |
| GO:0005737 cytoplasm | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetic inference of cytoplasmic activity for the cytosolic sulfotransferase family; consistent with GFP localization of AtSOT16-18. Reason: Experimentally supported by GFP fusion localization of all three desulfoglucosinolate SOTs in protoplasts. Supporting Evidence: PMID:16367753 All three desulfoglucosinolate AtSOT proteins are localized in the cytoplasm, as demonstrated by transient expression of fusion constructs with the green fluorescent protein in Arabidopsis protoplasts. |
| GO:0005737 cytoplasm | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt subcellular-location mapping to cytoplasm, based on the experimental GFP data. Reason: Consistent with direct experimental localization. Supporting Evidence: PMID:16367753 All three desulfoglucosinolate AtSOT proteins are localized in the cytoplasm, as demonstrated by transient expression of fusion constructs with the green fluorescent protein in Arabidopsis protoplasts. |
| GO:0005737 cytoplasm | ISM GO_REF:0000122 | ACCEPT | Summary: AtSubP predicted cytoplasmic localization. Reason: Consistent with direct experimental localization. Supporting Evidence: PMID:16367753 All three desulfoglucosinolate AtSOT proteins are localized in the cytoplasm, as demonstrated by transient expression of fusion constructs with the green fluorescent protein in Arabidopsis protoplasts. |
| GO:0008146 sulfotransferase activity | IEA GO_REF:0000002 | MODIFY | Summary: The enzyme sulfates both aromatic and aliphatic desulfoglucosinolates. Reason: Replace broad sulfotransferase activity with both supported substrate-class activities already present, rather than selecting one and discarding demonstrated breadth. Substrate preferences vary between enzymes and, for SOT18, between C24 and Col-0 alleles. Proposed replacements: aromatic desulfoglucosinolate sulfotransferase activity aliphatic desulfoglucosinolate sulfotransferase activity Supporting Evidence: PMID:16367753 Sulfotransferases (SOTs) catalyse the transfer of a sulfate group from 3'-phosphoadenosine 5'-phosphosulfate (PAPS) to an appropriate hydroxy group of various substrates PMID:16367753 Three of them, AtSOT16, AtSOT17 and AtSOT18, catalyse the sulfation of desulfoglucosinolates. |
| GO:0019761 glucosinolate biosynthetic process | IDA PMID:15358770 Desulfoglucosinolate sulfotransferases from Arabidopsis thal... | ACCEPT | Summary: Recombinant SOT17 (AtST5c) catalyzes sulfation of desulfoglucosinolates, the final step of core glucosinolate structure formation. Reason: The enzyme catalyzes a biosynthetic step of the glucosinolate core pathway (direct participation), so this process is a core annotation. Supporting Evidence: PMID:15358770 The three enzymes were shown to catalyze the final step in the biosynthesis of the glucosinolate (GS) core structure, the sulfation of desulfoglucosinolates (dsGSs). They accept a broad range of dsGSs as substrates. |
| GO:0047364 aromatic desulfoglucosinolate sulfotransferase activity | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT propagation of desulfoglucosinolate sulfotransferase activity within the Arabidopsis SOT16/17/18 clade (PTN004305968); the target is among the experimentally characterized donors, which is expected. Reason: SOT17 has direct in vitro activity with aromatic desulfobenzylglucosinolate as well as aliphatic substrates; all three clade members accept a broad range of desulfoglucosinolates. Supporting Evidence: PMID:15358770 The three enzymes were shown to catalyze the final step in the biosynthesis of the glucosinolate (GS) core structure, the sulfation of desulfoglucosinolates (dsGSs). They accept a broad range of dsGSs as substrates. |
| GO:0047364 aromatic desulfoglucosinolate sulfotransferase activity | IDA PMID:15358770 Desulfoglucosinolate sulfotransferases from Arabidopsis thal... | ACCEPT | Summary: Purified His-tagged SOT17 sulfated a broad range of desulfoglucosinolates, including aromatic (phenylalanine-derived) substrates, although it prefers long-chain methionine-derived substrates in competition. Reason: GO:0047364 is defined by conversion of desulfoglucotropaeolin (desulfobenzylglucosinolate) and indolylmethyl desulfoglucosinolate; the enzyme is active with these substrates, although aliphatic desulfoglucosinolates are its preferred physiological substrates. Supporting Evidence: PMID:15358770 The three enzymes were shown to catalyze the final step in the biosynthesis of the glucosinolate (GS) core structure, the sulfation of desulfoglucosinolates (dsGSs). They accept a broad range of dsGSs as substrates. PMID:15358770 long chain dsGSs derived from methionine are the preferred substrates of AtST5b and AtST5c |
| GO:0051923 sulfation | IBA GO_REF:0000033 | ACCEPT | Summary: Sulfation (addition of a sulfate group to a molecule) propagated across the cytosolic sulfotransferase family. Reason: SOT17 transfers the sulfate group from PAPS to desulfoglucosinolates, so it directly performs sulfation; the process is general, with glucosinolate biosynthesis being the specific biological context. Supporting Evidence: PMID:16367753 Sulfotransferases (SOTs) catalyse the transfer of a sulfate group from 3'-phosphoadenosine 5'-phosphosulfate (PAPS) to an appropriate hydroxy group of various substrates PMID:16367753 Three of them, AtSOT16, AtSOT17 and AtSOT18, catalyse the sulfation of desulfoglucosinolates. |
| GO:0120527 aliphatic desulfoglucosinolate sulfotransferase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Rhea/EC-based electronic annotation (RHEA:52724, EC 2.8.2.38) to aliphatic desulfoglucosinolate sulfotransferase activity. Reason: Core molecular function; experimentally supported by in vitro kinetics showing preference for long-chain methionine-derived aliphatic desulfoglucosinolates. Supporting Evidence: PMID:15358770 long chain dsGSs derived from methionine are the preferred substrates of AtST5b and AtST5c PMID:19077143 AtSOT17 showed an increased specific activity with increasing chain length of ds-Gl derived from methionine |
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Download this section (compressed HTML)Q: Do SOT16, SOT17 and SOT18 act redundantly in planta, and does loss of SOT17 alone shift the aliphatic glucosinolate chain-length profile?
Q: Which structural features of SOT17 underlie its increasing activity with longer methylthioalkyl side chains?
Experiment: Generate sot17 single and sot16 sot17 sot18 higher-order CRISPR mutants and profile desulfoglucosinolate accumulation and glucosinolate chain-length distribution in roots and leaves.
Experiment: Solve the crystal structure of SOT17 with PAP and a long-chain desulfoglucosinolate and test binding-pocket mutants for chain-length preference.
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