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PubMed · 8976092

[Amidophosphoribosyltransferase].

H Iwahana·M Itakura
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Abstract

Amidophosphoribosyltransferase (ATase) is the supposed regulatory allosteric enzyme of de novo purine nucleotide biosynthesis. ATase cDNAs and genomic DNAs were cloned from 15 different species. The chicken, rat, and human ATase genes and AIRC (aminoimidazole ribonucleotide carboxylase) genes are closely linked and divergently transcribed from an intergenic regions of 0.2-0.6 kb. The crystal structure of B. subtilis ATase was determined. The ATase tetramer is a doughnut-shaped molecule and each ATase subunit is organized in two domains of approximately equal size. The four [4 Fe-4 S] clusters are located at the corners of the tetramer. The activity of ATase is regulated positively by PRPP and negatively by GMP and AMP.

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AmidophosphoribosyltransferaseAnimalsChickensDNAGenomeHumansPhosphoribosyl PyrophosphateProtein ConformationPurine NucleotidesRatsRibose-Phosphate PyrophosphokinaseEnglish AbstractJournal ArticleReview

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H Iwahana, M Itakura. 1996. [Amidophosphoribosyltransferase].. https://pubmed.ncbi.nlm.nih.gov/8976092/

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PubMed2005

The purine synthesis gene Prat2 is required for Drosophila metamorphosis, as revealed by inverted-repeat-mediated RNA interference.

PRAT (phosphoribosylamidotransferase; E.C. 2.4.2.14) catalyzes the first reaction in de novo purine nucleotide biosynthesis. In Drosophila melanogaster, the Prat and Prat2 genes are both highly conserved with PRAT sequences from prokaryotes and eukaryotes. However, Prat2 organization and expression during development is different from Prat. We used RNA interference (RNAi) to knock down expression of both Prat and Prat2 to investigate their functions. Using the GAL4-UAS system, Prat RNAi driven by Act5c-GAL4 or tubP-GAL4 causes variable pupal lethality (48-100%) and approximately 50% female sterility, depending on the transgenic strains and drivers used. This observation agrees with the phenotype previously observed for Prat EMS-induced mutations. Prat2 RNAi driven by Act5C-GAL4 or tubP-GAL4 also results in variable pupal lethality (61-93%) with the different transgenic strains, showing that Prat2 is essential for fly development. However, Prat2 RNAi-induced arrested pupae have a head eversion defect reminiscent of the "cryptocephal" phenotype, whereas Prat RNAi-induced arrested pupae die later as pharate adults. We conclude that Prat2 is required during the prepupal stage while Prat is more important for the pupal stage. In addition, Prat and Prat2 double RNAi results in more severe pupal lethal phenotypes, suggesting that Prat and Prat2 have partially additive functions during Drosophila metamorphosis.

Amidophosphoribosyltransferase↗
PubMed2004

Molecular analysis of "de novo" purine biosynthesis in solanaceous species and in Arabidopsis thaliana.

Purine nucleotides are essential components to sustain plant growth and development. In plants they are either synthesized "de novo" during the process of purine biosynthesis or are recycled from purine bases and purine nucleosides throughout the salvage pathway. Comparison between animals, microorganisms and Arabidopsis, the first plant species with a completely sequenced genome, shows that plants principally use the same biochemical steps to synthesize purine nucleotides and possess all the essential genes and enzymes. Here we report on the cloning and molecular analysis of the complete purine biosynthesis pathway in plants, and the in planta functional analysis of PRPP (5-phosphoribosyl-1-pyrophoshate) amidotransferase (ATase), catalyzing the first committed step of the "de novo" purine biosynthesis. The cloning of the genes involved in the purine biosynthesis pathway was attained by a screening strategy with heterologous cDNA probes and by using S. cerevisiae mutants for complementation. Southern hybridization showed a complex genomic organization for these genes in solanaceous species and their organ- and developmental specific expression was analyzed by Northern hybridization. The specific role of ATase for plant growth and development was analyzed in transgenic tobacco plants exhibiting a reduced ATase activity and in an Arabidopsis T-DNA mutant (atd2) deficient for ATase2. The transgenic tobacco plants as well as the Arabidopsis mutant exhibit a specific and comparable phenotype, which is characterized by strong growth retardation and severe chlorosis in leaves. The formation of white leaves, but green cotyledons is a characteristic trait of the Arabidopsis atd2 mutant.

Amidophosphoribosyltransferase↗