PA1054 (shaA) encodes the large ShaAB subunit of the Sha (Mrp/Mnh/Pha) multisubunit Na+/H+ antiporter of Pseudomonas aeruginosa PAO1. It is a 933-residue integral membrane protein with about 22 predicted transmembrane helices. It is a fusion of an MrpA-type part (the NuoL/ND5-like antiporter-like domain plus the Mrp-specific C-terminal region) and an MrpB-type part (MnhB domain), as in other Gram-negative Mrp operons. PA1054 is the first gene of the six-gene sha cluster PA1054-PA1059. The cluster restores Na+ tolerance and Na+/H+ antiport to an E. coli strain lacking its major antiporters, but not when PA1054 is deleted. Disruption of PA1054 in P. aeruginosa causes severe Na+ sensitivity, lowers Na+ efflux and attenuates virulence and organ colonization in mouse infection models. In Mrp antiporters, MrpA carries putative proton and Na+ translocation pathways, but antiport needs the hetero-oligomeric complex of all subunits.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005886 plasma membrane | IEA GO_REF:0000044 | ACCEPT | Summary: Subcellular location mapping (cell membrane, multi-pass). PA1054 has about 22 predicted TM helices and is the large subunit of an inner-membrane Na+/H+ antiporter complex. Reason: Correct location; the Sha complex extrudes Na+ across the cytoplasmic membrane. Supporting Evidence: file:PSEAE/PA1054/PA1054-uniprot.txt TRANSMEM 77..96 PMID:16030218 genes PA1054 to PA1059 encode a Na+/H+ antiporter that is largely responsible for Na+ extrusion in P. aeruginosa |
| GO:0015385 sodium:proton antiporter activity | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from PTN000511949, the LUCA root of PTHR43373 (MrpA family, 16 reference leaves), seeded by the PseudoCAP IMP row for this gene and by a B. subtilis MrpA (Q9K2S2) IMP row. PA1054 is ShaAB of the Sha antiporter. The activity belongs to the hetero-oligomeric complex, to which MrpA contributes. Archaeal MBH has no MrpA homologue, so no MBH subunit is in this family; one leaf, Sulfolobus SSO1021, is named as a formate hydrogenlyase subunit (HycC). Reason: Core activity of the complex this protein belongs to, with direct evidence for PA1054 itself (the cluster lacking PA1054 does not restore antiport). The qualifier should be contributes_to (GO_CENTRAL defect below). Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN000511949 · PTN000511949 SUPPORTS TRANSFER Family-root IBD; right for MrpA/MnhA/ShaA proteins as a contribution to complex activity. The HycC-named Sulfolobus leaf is the only clear caveat. UniProtKB:Q9I4S0 · PA1054 (shaA) SUPPORTS TRANSFER PseudoCAP IMP; PMID:16030218 deleted PA1054 from the cluster and the antiport defect of E. coli TO114 was then not complemented. Sound as a contribution to the complex activity. UniProtKB:Q9K2S2 · B. subtilis MrpA SUPPORTS TRANSFER Independent experimental seed: B. subtilis mrpA deletion is Na+ sensitive and is complemented in trans by MrpA. 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:21236240 Deletion of either mrpA or mrpD from the Bacillus subtilis chromosome resulted in a Na+ and pH sensitive growth phenotype. PMID:29218041 In previous studies, none of the Mrp antiporters exhibited antiport activity with MrpA or MrpD alone. file:PSEAE/PA1054/PA1054-bioinformatics/RESULTS.md PTN000511949 is the root of the PTHR43373 tree (LUCA speciation node, is_family_root: True): 16 leaves in 15 organisms. |
| GO:0015385 sodium:proton antiporter activity | IMP PMID:16030218 Characterization of a multigene-encoded sodium/hydrogen anti... | ACCEPT | Summary: PseudoCAP IMP, one of two seeds of the PTN000511949 antiporter IBD. Kosono et al. showed that the six-gene cluster PA1054-PA1059 restores Na+/H+ antiport to an antiporter-deficient E. coli strain, and that it fails to do so when PA1054 is deleted. PA1054 was also disrupted in P. aeruginosa, with loss of Na+ tolerance and lower Na+ efflux. PA1054 has its own mutant phenotype (the only sha mutant the abstract reports), so IMP is the right code. Reason: PA1054 is the large subunit of the Na+/H+ antiporter and is required for its activity; core activity, kept. Because the activity needs the whole complex, the qualifier should be contributes_to (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:36241630 His248MrpA accepts the proton from Lys353MrpA and delivers it to the conserved Lys/Glu pair of the MrpA subunit |
| GO:0016020 membrane | IEA GO_REF:0000044 | MODIFY | Summary: Generic membrane location from the subcellular location mapping. Reason: True but general; GO:0005886 plasma membrane (already on this gene) is the supported location. Proposed replacements: plasma membrane Supporting Evidence: file:PSEAE/PA1054/PA1054-uniprot.txt TRANSMEM 77..96 |
| GO:0035725 sodium ion transmembrane transport | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from PTN000511949 (MrpA family root), sole-seeded by the PseudoCAP IMP row for PA1054. MrpA carries putative ion translocation pathways and is required for Na+ extrusion by the Mrp complex. The term suits the clade. Reason: Core process of the Sha complex in which PA1054 directly participates; the seed is a real PA1054 mutant phenotype (lower Na+ efflux). Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN000511949 · PTN000511949 SUPPORTS TRANSFER Na+ transmembrane transport fits MrpA-family subunits of Mrp antiporters. UniProtKB:Q9I4S0 · PA1054 (shaA) SUPPORTS TRANSFER Sole seed; PA1054 disruption decreased Na+ efflux (PMID:16030218). Supporting Evidence: PMID:16030218 Disruption of PA1054 resulted in severe Na+ sensitivity during growth and decreased Na+ efflux activity. PMID:21236240 Presumably, MrpA transports Na+ whereas MrpD transports H+ in opposite directions, resulting in antiporter activity. |
| GO:0035725 sodium ion transmembrane transport | IMP PMID:16030218 Characterization of a multigene-encoded sodium/hydrogen anti... | ACCEPT | Summary: PseudoCAP IMP, the sole seed of the PTN000511949 Na+ transport IBD. Disruption of PA1054 in P. aeruginosa caused severe Na+ sensitivity and decreased Na+ efflux, and the paper concludes the sha genes are largely responsible for Na+ extrusion. Reason: Direct mutant evidence on this gene for a process in which its product takes part as the large ion-translocating subunit; correct term and code. Supporting Evidence: PMID:16030218 Disruption of PA1054 resulted in severe Na+ sensitivity during growth and decreased Na+ efflux activity. PMID:16030218 genes PA1054 to PA1059 encode a Na+/H+ antiporter that is largely responsible for Na+ extrusion in P. aeruginosa |
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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 MrpA-family IBD at PTN000511949 reach Sulfolobus SSO1021, named as a formate hydrogenlyase subunit (HycC)?
Experiment: Make in-frame deletions separating the MrpA-like and MrpB-like parts of PA1054 and test which is needed for 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.
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