TpbA (tyrosine phosphatase related to biofilm formation A; PA3885) is a periplasmic dual-specificity protein phosphatase of Pseudomonas aeruginosa with a DUSP/PTP fold (Pfam Y_phosphatase2, Siw14-like) and an N-terminal signal peptide. It dephosphorylates the periplasmic domain of the membrane-anchored diguanylate cyclase TpbB (YfiN, PA1120), preferring phospho-Tyr48 over Tyr62, and also acts on phosphoserine and phosphothreonine. Dephosphorylation inactivates TpbB and lowers cellular c-di-GMP, which reduces Pel polysaccharide production, aggregation and biofilm formation; tpbA transcription is activated by Las quorum sensing, so TpbA links quorum sensing to c-di-GMP signalling. The purified enzyme hydrolyses p-nitrophenyl phosphate and phosphotyrosine peptides with vanadate-sensitive activity and a catalytic Cys132; crystal structures in ligand-free, phosphate-bound and phosphotyrosine-bound states show the canonical PTP loop and general-acid loop.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0004722 protein serine/threonine phosphatase activity | IEA GO_REF:0000003 | ACCEPT | Summary: EC 3.1.3.16 mapping (protein serine/threonine phosphatase). UniProt transfers the EC from the PA14 ortholog, which dephosphorylates TpbB at Ser/Thr as well as Tyr sites. Reason: Dual-specificity activity is reported for TpbA and its structure is consistent with pTyr, pSer and pThr hydrolysis. Supporting Evidence: PMID:25909591 has been shown to possess phosphatase activities for pNPP and phosphotyrosine peptides, and can dephosphorylate pTyr, pSer and pThr residues |
| GO:0004722 protein serine/threonine phosphatase activity | ISS GO_REF:0000024 | ACCEPT | Summary: ISS from the PA14 ortholog A0A0H2ZFK2 (98% identical, 4/218 differences). Same claim as the IEA row. Reason: Near-identical ortholog with reported Ser/Thr dephosphorylation of TpbB; consistent with the DUSP fold. Supporting Evidence: PMID:25909591 has been shown to possess phosphatase activities for pNPP and phosphotyrosine peptides, and can dephosphorylate pTyr, pSer and pThr residues PMID:25909591 is a dual specific tyrosine phosphatase (DUSP) that negatively regulates biofilm formation |
| GO:0004725 protein tyrosine phosphatase activity | EXP PMID:25909591 Structural and Biochemical Analysis of Tyrosine Phosphatase ... | ACCEPT | Summary: EXP (UniProt) from Xu et al. 2015 using PAO1 TpbA: efficient hydrolysis of two phosphotyrosine peptides from the TpbB periplasmic domain, with a preference for Tyr48. Reason: Direct assay of the PAO1 enzyme on physiological-substrate peptides. Supporting Evidence: PMID:25909591 TpbA efficiently catalyzes the hydrolysis of two phosphotyrosine peptides derived from the periplasmic domain of TpbB |
| GO:0004725 protein tyrosine phosphatase activity | IDA PMID:19543378 Connecting quorum sensing, c-di-GMP, pel polysaccharide, and... | ACCEPT | Summary: PseudoCAP IDA and one of nine seeds of the PTN001258896 phosphatase activity IBD. Ueda and Wood purified TpbA-cHis and showed pNPP hydrolysis and dephosphorylation of two phosphotyrosine peptides, inhibited by orthovanadate. The work used strain PA14 TpbA (PA14_13660), which differs from PAO1 PA3885 at 4 of 218 residues; this strain transfer is routine and does not affect the claim. Reason: Seed is SOUND: direct assay of purified enzyme with phosphotyrosine substrates, later reproduced with PAO1 TpbA (PMID:25909591). Supporting Evidence: PMID:19543378 The purified TpbA protein had phosphatase activity with p-nitrophenyl phosphate (pNPP) PMID:19543378 TpbA-cHis dephosphorylated both phosphotyrosine peptides PMID:25909591 TpbA efficiently catalyzes the hydrolysis of two phosphotyrosine peptides derived from the periplasmic domain of TpbB |
| GO:0004725 protein tyrosine phosphatase activity | IEA GO_REF:0000003 | ACCEPT | Summary: EC 3.1.3.48 mapping; same claim as the experimental rows. Reason: Consistent with direct biochemical evidence. Supporting Evidence: PMID:19543378 TpbA-cHis dephosphorylated both phosphotyrosine peptides PMID:25909591 TpbA efficiently catalyzes the hydrolysis of two phosphotyrosine peptides derived from the periplasmic domain of TpbB |
| GO:0016791 phosphatase activity | IBA GO_REF:0000033 | TOO GENERAL | Summary: IBA phosphatase activity from PTN001258896 (Siw14/PFA-DSP-like atypical DUSP clade; seeds include yeast SIW14, four Arabidopsis PFA-DSPs, rice DSP1, a Leishmania major protein and M. tuberculosis PtpB, and TpbA itself). TpbA in WITH/FROM is its expected self-seed. True for TpbA, but GO:0004725 protein tyrosine phosphatase activity, accepted here, is_a descendant (via phosphoprotein phosphatase activity). Reason: The generic node term is the right level for this mixed-substrate clade, but for TpbA it is entailed by the accepted GO:0004725 and GO:0004722. |
| GO:0042597 periplasmic space | IDA PMID:19543378 Connecting quorum sensing, c-di-GMP, pel polysaccharide, and... | ACCEPT | Summary: PseudoCAP IDA periplasmic space. Ueda and Wood fractionated cells into cytosolic, periplasmic and membrane fractions and found TpbA only in the periplasm (data not shown; the expression host appears to be E. coli). Consistent with the signal peptide and with a substrate site in the periplasmic domain of TpbB. Reason: Fractionation plus a predicted signal peptide and a periplasmic substrate site agree. Supporting Evidence: PMID:19543378 we found that TpbA exclusively localized in the periplasm PMID:19543378 Periplasmic TpbA dephosphorylates the membrane-anchored GGDEF protein TpbB at a tyrosine reside which deactivates GGDEF protein activity file:PSEAE/tpbA/tpbA-uniprot.txt SIGNAL 1..28 |
| GO:0042597 periplasmic space | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt subcellular location mapping to periplasmic space; same claim. Reason: Consistent with the IDA row and the signal peptide. Supporting Evidence: file:PSEAE/tpbA/tpbA-uniprot.txt SIGNAL 1..28 PMID:19543378 we found that TpbA exclusively localized in the periplasm |
| GO:0042597 periplasmic space | ISS GO_REF:0000024 | ACCEPT | Summary: ISS from the PA14 ortholog; same claim. Reason: Consistent with the IDA row. Supporting Evidence: PMID:19543378 we found that TpbA exclusively localized in the periplasm |
Loading supporting content…
Download this section (compressed HTML)Q: Which kinase phosphorylates the periplasmic tyrosines of TpbB, and is periplasmic tyrosine phosphorylation used by other P. aeruginosa membrane proteins?
Experiment: Identify the periplasmic kinase acting on TpbB Tyr48 by phosphoproteomics of tpbA mutants combined with candidate kinase deletions, and test whether TpbB phosphomimetic mutants bypass tpbA loss in c-di-GMP and biofilm assays.
Loading supporting content…
Download this section (compressed HTML)Loading supporting content…
Download this section (compressed HTML)