DVU_0279 is a SulP/SLC26 family secondary-active anion transporter with a C-terminal STAS (Sulfate Transporter and Anti-Sigma factor antagonist) regulatory domain. Despite being named "sulfate permease family protein," comparative genomic analysis indicates DVU_0279 phylogenetically clusters with DauA-like dicarboxylate transporters rather than with sulfate-selective SulP members. The protein is a multi-pass integral membrane protein with 8 predicted transmembrane helices. DVU_0279 is one of three SulP-type transporters in D. vulgaris Hildenborough (along with DVU0053 and DVU1999), but it is not essential for sulfate uptake; the organism relies primarily on CysZ transporters and possibly DVU0053 for sulfate import during dissimilatory sulfate reduction. The precise substrate specificity of DVU_0279 remains to be experimentally determined, but phylogenetic evidence suggests it may transport C4-dicarboxylates (e.g., succinate, fumarate) or related anions rather than sulfate.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0016020 membrane | IEA GO_REF:0000120 | MODIFY | Summary: The annotation to membrane (GO:0016020) is well-supported. UniProt predicts 8 transmembrane helices using Phobius. The protein contains both the SLC26A/SulP transmembrane domain (IPR011547) and a cytosolic STAS domain (IPR002645). The SLC26/SulP family members are established integral membrane transporters. However, GO:0016020 (membrane) is quite general; a more specific term like GO:0005886 (plasma membrane) would be appropriate since bacterial SulP/SLC26 transporters localize to the inner/cytoplasmic membrane. Reason: The term GO:0016020 (membrane) is correct but too general. Given that this is a bacterial secondary-active transporter of the SulP/SLC26 family with multiple transmembrane domains, it should localize to the bacterial inner membrane (plasma membrane). The evidence from family homology and predicted topology (8 TM helices) supports annotation to the more specific term GO:0005886 (plasma membrane). Proposed replacements: plasma membrane Supporting Evidence: file:DESVH/Q72FD5/Q72FD5-deep-research-falcon.md Inner (cytoplasmic) membrane integral transporter with cytosolic STAS tail, by homology to SulP/SLC26 architecture |
| GO:0055085 transmembrane transport | IEA GO_REF:0000002 | ACCEPT | Summary: The annotation to transmembrane transport (GO:0055085) is appropriate as a general biological process term. DVU_0279 belongs to the SLC26A/SulP family (IPR001902), which are established secondary-active transmembrane transporters. The SulP/SLC26 family operates via an elevator-type alternating access mechanism with multiple anion-binding sites. However, this process term is quite general and does not specify the substrate being transported. Reason: The annotation is correct. DVU_0279 is a member of the SulP/SLC26 family of anion transporters, which are well-characterized secondary-active transporters. While more specific process terms exist (such as GO:1902358 sulfate transmembrane transport), the evidence suggests DVU_0279 may not be primarily a sulfate transporter. The comparative genomics analysis places DVU_0279 with DauA-like dicarboxylate transporters, and it is not essential for sulfate uptake in D. vulgaris. Therefore, the general term GO:0055085 is appropriately conservative until experimental data clarify substrate specificity. Supporting Evidence: file:DESVH/Q72FD5/Q72FD5-deep-research-falcon.md DVU0279 clusters phylogenetically with dicarboxylate transporter DauA |
| GO:0008509 monoatomic anion transmembrane transporter activity | ISS file:DESVH/Q72FD5/Q72FD5-deep-research-falcon.md | NEW | Summary: This annotation is proposed based on domain architecture and family membership. The SLC26A/SulP family are established anion transporters that move inorganic anions (sulfate, bicarbonate, chloride, oxalate) across membranes. The STAS domain modulates transporter function. Reason: DVU_0279 contains the SLC26A/SulP domain (IPR011547, IPR001902), which defines a family of secondary-active anion transporters. While the precise substrate is unknown, family membership strongly supports annotation to monoatomic anion transmembrane transporter activity. This is more informative than no MF annotation while being appropriately general given the uncertainty about whether DVU_0279 transports sulfate vs. other anions. Supporting Evidence: file:DESVH/Q72FD5/Q72FD5-deep-research-falcon.md SulP/SLC26 transporters: A widely distributed family of secondary-active anion transporters that move inorganic anions (e.g., sulfate, bicarbonate, chloride, oxalate, iodide in some members) across membranes |
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Download this section (compressed HTML)Q: What is the actual substrate specificity of DVU_0279 - does it transport sulfate, dicarboxylates, or other anions?
Q: What is the physiological role of DVU_0279 in D. vulgaris metabolism given it is not essential for sulfate uptake?
Experiment: Express DVU_0279 in E. coli or Xenopus oocytes and measure uptake of radiolabeled substrates (35S-sulfate, 14C-succinate, 14C-fumarate) to determine substrate specificity and kinetics.
Hypothesis: DVU_0279 transports dicarboxylates rather than sulfate based on phylogenetic clustering with DauA
Type: transport assay
Experiment: Generate clean deletion of DVU_0279 and test growth on various carbon/energy sources including dicarboxylates to identify conditions where DVU_0279 is required.
Hypothesis: DVU_0279 knockout will show growth defects on dicarboxylate-containing media
Type: gene knockout phenotype
Experiment: Reconstitute purified DVU_0279 in liposomes or express in oocytes for voltage-clamp analysis to determine transport mechanism (symport, antiport) and coupling ion.
Hypothesis: DVU_0279 functions as a secondary-active transporter like other SulP family members
Type: electrophysiology
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