PA3170 encodes the 5'-methylthioadenosine (MTA) deaminase of Pseudomonas aeruginosa (PaMTADA), a zinc-dependent enzyme of the amidohydrolase superfamily (ATZ/TRZ subgroup). It deaminates MTA to 5'-methylthioinosine with very high catalytic efficiency (kcat/Km 1.6 x 10^7 per M per s) and also deaminates adenosine about 40-fold less efficiently, but not adenine, S-adenosylhomocysteine or guanosine. It is the only MTA-acting activity in P. aeruginosa extracts and begins the organism's unusual MTA salvage route, in which MTI is then cleaved by the MTI phosphorylase PA3004. MTA is a by-product of polyamine synthesis and of acyl-homoserine lactone synthesis by quorum-sensing synthases. Crystal structures with 5'-methylthiocoformycin show the transition-state mimic bound to the catalytic zinc.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0004000 adenosine deaminase activity | IDA PMID:23050701 Methylthioadenosine deaminase in an alternative quorum sensi... | KEEP AS NON CORE | Summary: PseudoCAP IDA seed of PTN005182504 (node term deaminase activity). Reason: Measured with purified enzyme at 3.7 x 10^5 per M per s, a genuine secondary activity; the enzyme prefers MTA 40-fold and the authors call it a specific MTA deaminase. PAO1 also has a dedicated adenosine deaminase (PA0148). Seed verdict SOUND for the node term. Supporting Evidence: PMID:23050701 causing most of the 40-fold lower catalytic efficiency (kcat/Km) on adenosine (3.7 Γ 105 Mβ1sβ1) |
| GO:0016787 hydrolase activity | IEA GO_REF:0000002 | TOO GENERAL | Summary: InterPro mapping to hydrolase activity. Reason: Entailed by GO:0090614. |
| GO:0016810 hydrolase activity, acting on carbon-nitrogen (but not peptide) bonds | IEA GO_REF:0000002 | TOO GENERAL | Summary: InterPro mapping to C-N hydrolase activity. Reason: Entailed by GO:0090614. |
| GO:0016814 hydrolase activity, acting on carbon-nitrogen (but not peptide) bonds, in cyclic amidines | IEA GO_REF:0000117 | TOO GENERAL | Summary: ARBA mapping to cyclic amidine hydrolase activity. Reason: Entailed by GO:0090614. |
| GO:0019239 deaminase activity | IBA GO_REF:0000033 | TOO GENERAL | Summary: IBA from PTN005182504, seeded by Xcc2270 (Q8P8H1), MJ1541 (Q58936), Tm0936 (Q9X034), Bc1793 (Q81F14) and this gene. Reason: True; entailed by GO:0090614 5'-methylthioadenosine deaminase activity (is_a deaminase activity), accepted here. The generic node term suits a clade whose members deaminate different adenine compounds. |
| GO:0019239 deaminase activity | IEA GO_REF:0000117 | TOO GENERAL | Summary: ARBA mapping to deaminase activity. Reason: Entailed by GO:0090614. |
| GO:0090614 5'-methylthioadenosine deaminase activity | IDA PMID:23968233 Structure-guided discovery of new deaminase enzymes. | ACCEPT | Summary: IDA from the CACAO-curated structure-guided enzymology paper. Reason: Core activity, confirmed in two independent studies. Supporting Evidence: PMID:23968233 The four enzymes from sg-2 can deaminate MTA but not SAH. PMID:23050701 The substrate specificity reveals PA3170 protein to be a specific MTA deaminase. |
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Experiment: Measure intracellular MTA, AHL and autoinducer-2 levels in a PA3170 deletion mutant and in wild type treated with 5'-methylthiocoformycin.
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