Methylthioadenosine deaminase in an alternative quorum sensing pathway in Pseudomonas aeruginosa
| Autor: | Meng-Chiao Ho, Peter C. Tyler, Richard F.G. Fröhlich, Steven C. Almo, Vern L. Schramm, Rong Guan |
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| Rok vydání: | 2012 |
| Předmět: |
Models
Molecular Adenosine Deaminase Molecular Sequence Data Nucleoside Deaminases Biology medicine.disease_cause Crystallography X-Ray Methylthioinosine Biochemistry Article Substrate Specificity Coformycin Ligases chemistry.chemical_compound Glycogen phosphorylase Adenosine deaminase Deoxyadenosine medicine Humans Amino Acid Sequence Hypoxanthine Phosphorolysis Thionucleosides Deoxyadenosines Pseudomonas aeruginosa Quorum Sensing Adenosine chemistry biology.protein Sequence Alignment medicine.drug |
| Zdroj: | Biochemistry. 51(45) |
| ISSN: | 1520-4995 |
| Popis: | Pseudomonas aeruginosa possesses an unusual pathway for 5'-methylthioadenosine (MTA) metabolism involving deamination to 5'-methylthioinosine (MTI) followed by N-ribosyl phosphorolysis to hypoxanthine and 5-methylthio-α-d-ribose 1-phosphate. The specific MTI phosphorylase of P. aeruginosa has been reported [Guan, R., Ho, M. C., Almo, S. C., and Schramm, V. L. (2011) Biochemistry 50, 1247-1254], and here we characterize MTA deaminase from P. aeruginosa (PaMTADA). Genomic analysis indicated the PA3170 locus to be a candidate for MTA deaminase (MTADA). Protein encoded by PA3170 was expressed and shown to deaminate MTA with 40-fold greater catalytic efficiency for MTA than for adenosine. The k(cat)/K(m) value of 1.6 × 10(7) M(-1) s(-1) for MTA is the highest catalytic efficiency known for an MTA deaminase. 5'-Methylthiocoformycin (MTCF) is a 4.8 pM transition state analogue for PaMTADA but causes no significant inhibition of human adenosine deaminase or MTA phosphorylase. MTCF is permeable to P. aeruginosa and exhibits an IC(50) of 3 nM on cellular PaMTADA activity. PaMTADA is the only activity in P. aeruginosa extracts to act on MTA. MTA and 5-methylthio-α-d-ribose are involved in quorum sensing pathways; thus, PaMTADA is a potential target for quorum sensing. The crystal structure of PaMTADA in complex with MTCF shows the transition state mimic 8(R)-hydroxyl group in contact with a catalytic site Zn(2+), the 5'-methylthio group in a hydrophobic pocket, and the transition state mimic of the diazepine ring in contact with a catalytic site Glu. |
| Databáze: | OpenAIRE |
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