PstS is the exported periplasmic solute-binding subunit of the high-affinity PstSACB ABC phosphate importer. It binds inorganic phosphate with high selectivity in the periplasm and presents liganded phosphate to the PstA/PstC membrane subunits for ATP-dependent uptake by the PstB-powered transporter.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0006817 phosphate ion transport | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: PstS is the phosphate-binding subunit of the high-affinity Pst transporter. Reason: The PAINT assertion captures the correct inherited role in phosphate uptake, and E. coli genetics also places phoS/pstS in P(i) transport. This broad parent is retained as non-core because the specific process is phosphate ion transmembrane transport. Supporting Evidence: PMID:4570598 the phoS and phoT genes are primarily involved in P(i) transport |
| GO:0006817 phosphate ion transport | IDA PMID:4570598 Inorganic phosphate transport in Escherichia coli: involveme... | KEEP AS NON CORE | Summary: phoS/pstS mutants alter phosphate uptake through the Pst system. Reason: The early transport genetics correctly implicates phoS/pstS in phosphate uptake. The annotation is a correct but broader parent of the more precise phosphate ion transmembrane transport process. Supporting Evidence: PMID:4570598 the phoS and phoT genes are primarily involved in P(i) transport |
| GO:0006974 DNA damage response | IEP PMID:11967071 Over 1000 genes are involved in the DNA damage response of E... | MARK AS OVER ANNOTATED | Summary: pstS expression changed in a broad mitomycin C expression survey. Reason: Khil and Camerini-Otero measured global transcript changes after DNA damage and found expression changes for nearly one third of E. coli genes. This is expression-response evidence rather than evidence that PstS directly executes DNA repair or a DNA-damage response step. Supporting Evidence: PMID:11967071 a large number of genes (nearly 30% of all genes) displayed significant changes in their expression level |
| GO:0009314 response to radiation | IMP PMID:27718375 Screen for genes involved in radiation survival of Escherich... | MARK AS OVER ANNOTATED | Summary: The pstS deletion was recovered in a radiation-sensitivity screen. Reason: The Keio collection screen can identify mutants that are hypersensitive to irradiation for indirect envelope, growth, or homeostasis reasons. PstS has a direct role in periplasmic phosphate capture, so a radiation-survival phenotype is retained as a secondary perturbation rather than a core response-to-radiation function. Supporting Evidence: PMID:27718375 A set of 3907 single-gene knockout (Keio collection) strains of Escherichia coli K-12 was examined for strains with increased susceptibility to killing by X- or UV-radiation. |
| GO:0016020 membrane | NAS PMID:3881386 Phosphate-specific transport system of Escherichia coli: nuc... | REMOVE | Summary: PstS is a periplasmic binding protein, not an integral membrane protein. Reason: PstS participates in a membrane ABC transporter, but the mature E. coli protein is exported as a soluble outer membrane-bounded periplasmic substrate-binding protein rather than located in the membrane. The precise periplasm annotation is already supported by the phoS signal sequence and mature-protein assignment. Supporting Evidence: PMID:6321434 the structural gene for the phosphate-repressible, periplasmic phosphate-binding protein |
| GO:0030288 outer membrane-bounded periplasmic space | IDA PMID:6321434 Structural gene for the phosphate-repressible phosphate-bind... | ACCEPT | Summary: PstS is synthesized with an N-terminal signal peptide and functions in the periplasm. Reason: The phoS sequence encodes a precursor with a signal sequence that yields the mature periplasmic phosphate-binding protein. Supporting Evidence: PMID:6321434 The phosphate-binding protein is synthesized in a precursor form which includes an additional N-terminal segment containing 25 amino acid residues |
| GO:0035435 phosphate ion transmembrane transport | IEA GO_REF:0000002 | ACCEPT | Summary: The PstS-family signature correctly maps to phosphate import by PstSACB. Reason: PstS family proteins are the phosphate-capture subunits that feed the high-affinity ABC importer; E. coli PstS is the periplasmic binding protein of this transporter. |
| GO:0035435 phosphate ion transmembrane transport | NAS PMID:3881386 Phosphate-specific transport system of Escherichia coli: nuc... | ACCEPT | Summary: PstS is a phosphate-capture subunit of the PstSACB transporter. Reason: The sequenced phoS-pstC-pstA-pstB-phoU region encodes the phosphate-specific transport system, and PstS contributes the periplasmic phosphate-binding step needed before translocation. Supporting Evidence: PMID:3881386 The complete sequence is transcribed counterclockwise, in the order phoS pstC pstA pstB phoU. |
| GO:0042301 phosphate ion binding | IDA PMID:2215649 High specificity of a phosphate transport protein determined... | ACCEPT | Summary: Crystal structures show phosphate bound in the PstS/PBP ligand cleft. Reason: The refined liganded PstS structure established the atomic basis of phosphate selectivity and directly supports inorganic phosphate binding as PstS's core molecular activity. Supporting Evidence: PMID:2215649 the highly refined 1.7 A resolution X-ray structure of the liganded form of the phosphate-binding protein |
| GO:0042301 phosphate ion binding | IEA GO_REF:0000002 | ACCEPT | Summary: The PstS InterPro family is a phosphate-binding protein family. Reason: The InterPro2GO mapping matches the experimentally characterized E. coli PstS protein, whose crystallographic ligand is phosphate. Supporting Evidence: PMID:2215649 the atomic features responsible for phosphate selectivity, either in monobasic or dibasic form, and the exclusion of sulphate |
| GO:0042597 periplasmic space | IEA GO_REF:0000044 | MODIFY | Summary: UniProt correctly places the mature PstS protein in the periplasm. Reason: In Gram-negative E. coli, the more precise cellular component is outer membrane-bounded periplasmic space rather than the cross-taxon periplasmic-space parent. Proposed replacements: outer membrane-bounded periplasmic space Supporting Evidence: file:ECOLI/pstS/pstS-uniprot.txt Periplasm. |
| GO:0043190 ATP-binding cassette (ABC) transporter complex | IEA GO_REF:0000002 | MODIFY | Summary: PstS is part of a substrate-binding-subunit-containing ABC importer. Reason: PstS is specifically a solute-binding subunit of the PstSACB ABC importer, so the child term for ABC transporter complexes that include a substrate-binding subunit is a better component annotation. Proposed replacements: ATP-binding cassette (ABC) transporter complex, substrate-binding subunit-containing Supporting Evidence: file:ECOLI/pstS/pstS-uniprot.txt ABC transporter complex PstSACB |
| GO:0055052 ATP-binding cassette (ABC) transporter complex, substrate-binding subunit-containing | NAS PMID:3881386 Phosphate-specific transport system of Escherichia coli: nuc... | ACCEPT | Summary: PstS is the substrate-binding protein of PstSACB. Reason: The GO term precisely describes the binding-protein-dependent ABC importer complex in which PstS is the periplasmic phosphate-capture subunit. Supporting Evidence: file:ECOLI/pstS/pstS-uniprot.txt ABC transporter complex PstSACB |
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Download this section (compressed HTML)Q: Which liganded and unliganded conformations of E. coli PstS productively dock onto PstA/PstC during the PstSACB transport cycle?
Experiment: Reconstitute purified E. coli PstS with PstA/PstC/PstB proteoliposomes and compare phosphate binding, PstS docking, ATP hydrolysis, and phosphate uptake with binding-site or docking-surface PstS variants.
Type: in vitro transporter reconstitution
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