PA0148 is the adenine deaminase of Pseudomonas aeruginosa, a mononuclear zinc enzyme of the amidohydrolase superfamily (adenosine/AMP deaminase family, group 3 of cog1816) long misannotated as an adenosine deaminase. The purified enzyme hydrolytically deaminates adenine to hypoxanthine and ammonia with kcat/Km above 10^5 M-1 s-1, also accepts 6-chloropurine, 6-methoxypurine, N6-methyladenine and 2,6-diaminopurine, and has no detectable activity on adenosine. Crystal structures with adenine, hypoxanthine and 6-chloropurine show a distorted (beta/alpha)8 barrel with one zinc ion bound by His16, His18, His196 and Asp277, and a tyrosine that blocks the ribose pocket. By converting adenine to hypoxanthine it feeds purine salvage and catabolism.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000034 adenine deaminase activity | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from PTN000150991 (adenine deaminase clade, 6 seeds, 14 leaf IBAs). Seeds include yeast AAH1, S. pombe SPBC1198.02, three other bacterial/protist members and PA0148 itself. Reason: PA0148 has its own purified-enzyme kinetics and co-crystal structures for this activity; the node term suits the clade and the IBD stands on the five other seeds. Supporting Evidence: PMID:21710971 All of these proteins will deaminate adenine to produce hypoxanthine with k(cat)/K(m) values that exceed 10(5) M(-1) s(-1). |
| GO:0000034 adenine deaminase activity | IDA PMID:21710971 Pa0148 from Pseudomonas aeruginosa catalyzes the deamination... | ACCEPT | Summary: PseudoCAP IDA, the PTN000150991 seed row. Purified PA0148 deaminates adenine to hypoxanthine (product confirmed by mass spectrometry) and does not act on adenosine. Reason: Seed verdict SOUND; full text read, direct kinetics and structures of the gene product. Supporting Evidence: PMID:21710971 All of these proteins will deaminate adenine to produce hypoxanthine with k(cat)/K(m) values that exceed 10(5) M(-1) s(-1). PMID:21710971 Adenosine is not a substrate for any of these enzymes. |
| GO:0000034 adenine deaminase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Combined automated adenine deaminase activity. Reason: Same claim as the IDA row. Supporting Evidence: PMID:21710971 All of these proteins will deaminate adenine to produce hypoxanthine with k(cat)/K(m) values that exceed 10(5) M(-1) s(-1). |
| GO:0006146 adenine catabolic process | IBA GO_REF:0000033 | ACCEPT | Summary: IBA adenine catabolic process. Reason: Deamination of adenine to hypoxanthine is the first step of adenine breakdown, and PA0148 catalyses it; it is the only adenine deaminase class found in a given bacterium according to the characterising paper. Supporting Evidence: PMID:21710971 Although there is overlap between the types of bacteria that possess a specific adenine deaminase, each species of bacteria appears to possess only one adenine deaminase. |
| GO:0006146 adenine catabolic process | IEA GO_REF:0000120 | ACCEPT | Summary: Combined automated adenine catabolic process. Reason: Same claim as the IBA row. Supporting Evidence: PMID:21710971 All of these proteins will deaminate adenine to produce hypoxanthine with k(cat)/K(m) values that exceed 10(5) M(-1) s(-1). |
| GO:0008270 zinc ion binding | IEA GO_REF:0000104 | ACCEPT | Summary: Zinc ion binding. Reason: The purified enzyme contains zinc and the crystal structure shows a single active-site zinc coordinated by His16, His18, His196 and Asp277. Supporting Evidence: PMID:21710971 Pa0148 and AAur1117 contained, on average, 0.5 and 0.9 equivalents of Zn2+ per monomer. |
| GO:0019239 deaminase activity | IEA GO_REF:0000002 | TOO GENERAL | Summary: Generic deaminase activity from adenosine/AMP deaminase domain signatures. Reason: True but uninformative; GO:0000034 adenine deaminase activity, accepted in this review, is an is_a descendant of GO:0019239. |
| GO:0043103 hypoxanthine salvage | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: IBA hypoxanthine salvage from yeast AAH1 and S. pombe seeds. Reason: PA0148 produces hypoxanthine from adenine, which fits the GO definition of generating hypoxanthine from a derivative without de novo synthesis, and the yeast seeds show this role in vivo. Its physiological use in P. aeruginosa (salvage to IMP versus catabolism) has not been tested, so the term is kept as a plausible but peripheral process. Supporting Evidence: PMID:21710971 All of these proteins will deaminate adenine to produce hypoxanthine with k(cat)/K(m) values that exceed 10(5) M(-1) s(-1). |
| GO:0043103 hypoxanthine salvage | IEA GO_REF:0000104 | KEEP AS NON CORE | Summary: UniRule hypoxanthine salvage. Reason: Same claim as the IBA row. Supporting Evidence: PMID:21710971 All of these proteins will deaminate adenine to produce hypoxanthine with k(cat)/K(m) values that exceed 10(5) M(-1) s(-1). |
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Download this section (compressed HTML)Q: Does P. aeruginosa use PA0148 mainly to salvage adenine via hypoxanthine to IMP, or to catabolise adenine as a nitrogen source?
Experiment: Compare growth of a PA0148 deletion mutant with adenine as sole nitrogen source and in a purine auxotroph background supplied with adenine, with complementation.
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