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Query: UNIPROT:P06889 (
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630,302
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
This report describes the isolation of the genes encoding allantoicase (DAL2) and
ureidoglycolate hydrolase
(DAL3), which are components of the large DAL gene cluster on the right arm of chromosome IX of Saccharomyces cerevisiae. During this work a new gene (DAL7) was identified and found to be regulated in the manner expected for an allantoin pathway gene. Its expression was (i) induced by allophanate, (ii) sensitive to nitrogen catabolite repression, and (iii) responsive to mutation of the DAL80 and DAL81 loci, which have previously been shown to regulate the allantoin degradation system. Hybridization probes generated from these cloned genes were used to analyze expression of the allantoin pathway genes in wild-type and mutant cells grown under a variety of physiological conditions. When comparison was possible, the patterns of mRNA and enzyme levels observed in various strains and physiological conditions were very similar, suggesting that the system is predominantly regulated at the level of gene expression. Although all of the genes seem to be controlled by a common mechanism, their detailed patterns of expression were, at the same time, highly individual and diverse.
Mol
Cell Biol 1985 Sep
PMID:Identification of the ureidoglycolate hydrolase gene in the DAL gene cluster of Saccharomyces cerevisiae. 391 39
In plants, the ureide pathway is a metabolic route that converts the ring nitrogen atoms of purine into ammonia via sequential enzymatic reactions, playing an important role in nitrogen recovery. In the final step of the pathway,
(S)-ureidoglycolate amidohydrolase
(UAH) catalyzes the conversion of (S)-ureidoglycolate into glyoxylate and releases two molecules of ammonia as by-products. UAH is homologous in structure and sequence with allantoate amidohydrolase (AAH), an upstream enzyme in the pathway with a similar function as that of an amidase but with a different substrate. Both enzymes exhibit strict substrate specificity and catalyze reactions in a concerted manner, resulting in purine degradation. Here, we report three crystal structures of Arabidopsis thaliana UAH (bound with substrate, reaction intermediate, and product) and a structure of Escherichia coli AAH complexed with allantoate. Structural analyses of UAH revealed a distinct binding mode for each ligand in a bimetal reaction center with the active site in a closed conformation. The ligand directly participates in the coordination shell of two metal ions and is stabilized by the surrounding residues. In contrast, AAH, which exhibits a substrate-binding site similar to that of UAH, requires a larger active site due to the additional ureido group in allantoate. Structural analyses and mutagenesis revealed that both enzymes undergo an open-to-closed conformational transition in response to ligand binding and that the active-site size and the interaction environment in UAH and AAH are determinants of the substrate specificities of these two structurally homologous enzymes.
J
Mol
Biol 2014 Aug 26
PMID:Structural insights into the substrate specificity of (s)-ureidoglycolate amidohydrolase and its comparison with allantoate amidohydrolase. 2502 Feb 32