PA1059 encodes subunit G (ShaG/MrpG) of the Sha (Mrp/Mnh/Pha) multisubunit Na+/H+ antiporter of Pseudomonas aeruginosa PAO1. It is a small (115 residues) integral membrane protein with three predicted transmembrane helices, in the PhaG/MnhG/YufB family. It is the last gene of the six-gene sha cluster PA1054-PA1059, in which shaA and shaB are fused. The cluster restores Na+ tolerance and Na+/H+ antiport to an E. coli strain lacking its major antiporters, and in P. aeruginosa the Sha antiporter is largely responsible for Na+ extrusion and supports virulence in mouse infection models. In Bacillus Mrp antiporters, a conserved proline of MrpG (Pro81) is needed for Na+/H+ antiport. Its homologue in archaeal membrane-bound hydrogenase is MBH subunit C.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0015297 antiporter activity | IEA GO_REF:0000002 | MODIFY | Summary: InterPro2GO from the PhaG/MnhG/YufB family. Correct but general. Reason: True but general; GO:0015385 sodium:proton antiporter activity (a descendant, already on this gene) is the supported activity, to which this subunit contributes as part of the complex. Proposed replacements: sodium:proton antiporter activity Supporting Evidence: PMID:16030218 The gene cluster PA1054 to PA1059, but not the cluster with a deletion of PA1054, complemented a growth defect in the presence of 0.2 M NaCl and a defect in Na+/H+ antiport activity of the Escherichia coli TO114 mutant lacking the three major Na+/H+ antiporters |
| GO:0015385 sodium:proton antiporter activity | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from PTN002162936, the LUCA root of PTHR34703 (MrpG family, 19 reference leaves, plus TreeGrafter propagations), sole-seeded by the PseudoCAP IMP row for this gene. PA1059 is ShaG of the Sha antiporter. The activity belongs to the hetero-oligomeric complex, so a subunit contributes to it. The node also covers MBH/MBX hydrogenase subunit C proteins (TK2082, TK1224). Reason: The core activity of the complex this protein belongs to; kept, with the qualifier corrected to contributes_to (GO_CENTRAL defect). Propagation Review Root cause: SOURCE WEAK OR INFERRED Sources checked: PANTHER:PTN002162936 · PTN002162936 SUPPORTS TRANSFER Family-root IBD; right for Mrp/Mnh/Pha subunit G as a contribution to complex activity. It reaches MBH/MBX hydrogenase subunits, where a Na+/H+ antiporter MF is doubtful. UniProtKB:Q9I4R5 · PA1059 (shaG) SOURCE WEAK OR INFERRED Sole seed; PseudoCAP IMP, but the PMID:16030218 abstract reports a disruption of PA1054 only. Supporting Evidence: PMID:16030218 The gene cluster PA1054 to PA1059, but not the cluster with a deletion of PA1054, complemented a growth defect in the presence of 0.2 M NaCl and a defect in Na+/H+ antiport activity of the Escherichia coli TO114 mutant lacking the three major Na+/H+ antiporters PMID:29754813 Indeed, MBH subunit C P88 is equivalent to P81 in MrpG and in a previous study it was demonstrated that the H+/Na+ antiporter activity of Mrp was abolished when P81 is substituted by an alanine or a glycine file:PSEAE/PA1059/PA1059-bioinformatics/RESULTS.md PTN002162936 is the root of the PTHR34703 tree (LUCA speciation node, is_family_root: True): 19 leaves in 16 organisms |
| GO:0015385 sodium:proton antiporter activity | IMP PMID:16030218 Characterization of a multigene-encoded sodium/hydrogen anti... | ACCEPT | Summary: PseudoCAP IMP, the sole seed of the PTN002162936 antiporter IBD. The paper shows antiport for the whole PA1054-PA1059 cluster, lost when PA1054 is deleted, and reports a P. aeruginosa disruption of PA1054 only. The abstract describes no PA1059 mutant, and the full text (read 2026-11-05) confirms none was made, so a mutant-phenotype code is wrong for PA1059. PA1059 is a subunit of the antiporter complex. Reason: PA1059 is part of the Na+/H+ antiporter, so the claim is kept as the core activity. It is a contribution (contributes_to), and the evidence is cluster-level, with no PA1059 mutant in the paper (full text checked). Both are flagged to PseudoCAP. Supporting Evidence: PMID:16030218 The gene cluster PA1054 to PA1059, but not the cluster with a deletion of PA1054, complemented a growth defect in the presence of 0.2 M NaCl and a defect in Na+/H+ antiport activity of the Escherichia coli TO114 mutant lacking the three major Na+/H+ antiporters PMID:20624916 Antiport activity requires hetero-oligomeric complexes of all six or seven hydrophobic Mrp proteins (MrpA-MrpG). |
| GO:0035725 sodium ion transmembrane transport | IMP PMID:16030218 Characterization of a multigene-encoded sodium/hydrogen anti... | ACCEPT | Summary: PseudoCAP IMP. It seeds no IBD (PTN002162936 carries no GO:0035725 annotation). The Sha cluster is responsible for Na+ efflux, and PA1059 is one of its subunits. The IMP code looks wrong for PA1059 (no PA1059 mutant in the abstract). Reason: Process correct for this subunit of the Na+-extruding complex; MrpG Pro81 is needed for Mrp antiport. Evidence code flagged. Supporting Evidence: PMID:16030218 genes PA1054 to PA1059 encode a Na+/H+ antiporter that is largely responsible for Na+ extrusion in P. aeruginosa PMID:29218041 MrpG-P81A in category 7 did not retain Na+/H+ antiport activity, but it was able to complement the sodium sensitivity of the E. coli KNabc. |
| GO:0055085 transmembrane transport | IEA GO_REF:0000002 | MODIFY | Summary: InterPro2GO from the PhaG/MnhG/YufB family. Correct but general. Reason: True but general; GO:0035725 sodium ion transmembrane transport (a descendant, already on this gene) is the supported process. Proposed replacements: sodium ion transmembrane transport Supporting Evidence: PMID:16030218 genes PA1054 to PA1059 encode a Na+/H+ antiporter that is largely responsible for Na+ extrusion in P. aeruginosa |
| GO:0005886 plasma membrane | IC PMID:16030218 Characterization of a multigene-encoded sodium/hydrogen anti... | NEW | Summary: PA1059 has no cellular component annotation. It has three predicted TM helices and is a subunit of the Sha Na+/H+ antiporter, which extrudes Na+ across the cytoplasmic membrane; in the Mrp structure MrpG is a three-helix membrane subunit of the complex. Reason: Two independent lines agree: the predicted TM helices of PA1059 and its membership in the inner-membrane Sha antiporter. All other Sha subunits (PA1054-PA1058) carry plasma membrane. IC records that the location is inferred from these lines, not assayed. Supporting Evidence: file:PSEAE/PA1059/PA1059-uniprot.txt TRANSMEM 12..33 PMID:16030218 genes PA1054 to PA1059 encode a Na+/H+ antiporter that is largely responsible for Na+ extrusion in P. aeruginosa PMID:36241630 Each of the small subunits MrpC, MrpF, and MrpG consists of a linear arrangement of three TMH each. |
Loading supporting content…
Download this section (compressed HTML)Q: Should GO provide a cellular component term for the Mrp-type multisubunit Na+/H+ antiporter complex, by analogy with GO:1903103 potassium:proton antiporter complex, so that Sha/Mrp subunits can be annotated to the complex instead of each carrying the activity?
Q: Should the subunit G IBD at PTN002162936 reach MBH/MBX hydrogenase subunit C proteins (TK2082, TK1224)?
Experiment: Make an in-frame PA1059 (shaG) deletion and a ShaG proline-to-alanine mutant at the position equivalent to B. subtilis MrpG Pro81, then test Na+ tolerance, Na+ efflux and Sha complex assembly (BN-PAGE); assay Na+/H+ antiport in everted vesicles of E. coli TO114 carrying each variant cluster.
Loading supporting content…
Download this section (compressed HTML)Loading supporting content…
Download this section (compressed HTML)Loading supporting content…
Download this section (compressed HTML)