Publications

• Chemical basis of nitrogen recovery through the ureide pathway: formation and hydrolysis of S-ureidoglycine in plants and bacteria.

  Serventi F., Ramazzina I., Lamberto I., Puggioni V., Gatti R., Percudani R.

  While some organisms, including humans, eliminate oxidized purines to get rid of excess nitrogen, for many others the recovery of the purine ring nitrogen is vital. In the so-called ureide pathway, nitrogen is released as ammonia from allantoate through a series of reactions starting with allantoa ... >> More

  While some organisms, including humans, eliminate oxidized purines to get rid of excess nitrogen, for many others the recovery of the purine ring nitrogen is vital. In the so-called ureide pathway, nitrogen is released as ammonia from allantoate through a series of reactions starting with allantoate amidohydrolase (AAH), a manganese-dependent enzyme found in plants and bacteria. We report NMR evidence that the true product of the AAH reaction is S-ureidoglycine, a nonstandard alpha-amino acid that spontaneously releases ammonia in vitro. Using gene proximity and logical genome analysis, we identified a candidate gene (ylbA) for S-ureidoglycine metabolism. The proteins encoded by Escherichia coli and Arabidopsis thaliana genes catalyze the manganese-dependent release of ammonia through hydrolysis of S-ureidoglycine. Hydrolysis then inverts the configuration and yields S-ureidoglycolate. S-Ureidoglycine aminohydrolase (UGHY) is cytosolic in bacteria, whereas in plants it is localized, like allantoate amidohydrolase, in the endoplasmic reticulum. These findings strengthen the basis for the known sensitivity of the ureide pathway to Mn availability and suggest a further rationale for the active transport of Mn in the endoplasmic reticulum of plant cells. << Less

  ACS Chem. Biol. 5:203-214(2010) [PubMed] [EuropePMC]

• Structural analysis of a ternary complex of allantoate amidohydrolase from Escherichia coli reveals its mechanics.

  Agarwal R., Burley S.K., Swaminathan S.

  Purine metabolism plays a major role in regulating the availability of purine nucleotides destined for nucleic acid synthesis. Allantoate amidohydrolase catalyzes the conversion of allantoate to (S)-ureidoglycolate, one of the crucial alternate steps in purine metabolism. The crystal structure of ... >> More

  Purine metabolism plays a major role in regulating the availability of purine nucleotides destined for nucleic acid synthesis. Allantoate amidohydrolase catalyzes the conversion of allantoate to (S)-ureidoglycolate, one of the crucial alternate steps in purine metabolism. The crystal structure of a ternary complex of allantoate amidohydrolase with its substrate allantoate and an allosteric effector, a sulfate ion, from Escherichia coli was determined to understand better the catalytic mechanism and substrate specificity. The 2.25 A resolution X-ray structure reveals an alpha/beta scaffold akin to zinc exopeptidases of the peptidase M20 family and lacks the (beta/alpha)(8)-barrel fold characteristic of the amidohydrolases. Arrangement of the substrate and the two co-catalytic zinc ions at the active site governs catalytic specificity for hydrolysis of N-carbamyl versus the peptide bond in exopeptidases. In its crystalline form, allantoate amidohydrolase adopts a relatively open conformation. However, structural analysis reveals the possibility of a significant movement of domains via rotation about two hinge regions upon allosteric effector and substrate binding resulting in a closed catalytically competent conformation by bringing the substrate allantoate closer to co-catalytic zinc ions. Two cis-prolyl peptide bonds found on either side of the dimerization domain in close proximity to the substrate and ligand-binding sites may be involved in protein folding and in preserving the integrity of the catalytic site. << Less

  J. Mol. Biol. 368:450-463(2007) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.

• Reversible activation of allantoate amidohydrolase by acid-pretreatment and other properties of the enzyme.

  Vogels G.D.

  Biochim Biophys Acta 113:277-291(1966) [PubMed] [EuropePMC]