Biomaterial Database

Phenylketonuric Tetrahymena: phenylalanine hydroxylase mutants and other tyrosine auxotrophs. 1981

Y M Sanford, and E Orias

Nineteen tyrosine auxotrophs of the ciliated protozoan Tetrahymena thermophila have been isolated and biochemically examined. These mutants are defective in the conversion of phenylalanine to tyrosine; this is analogous to the defect that causes phenylketonuria in humans. After nitrosoguanidine mutagenesis and self-fertilization, progeny clones were screened for tyrosine auxotrophy and positively identified by using growth tests and in vivo radiometric assays for phenylalanine-to-tyrosine conversion. Mutants in one complementation group (locus) lacked phenylalanine hydroxylase activity; mutants in three other loci appeared to be deficient in the unconjugated pteridine cofactor that is necessary for the function of the hydroxylase. Another mutant lacked the dihydropteridine reductase activity required to regenerate the reduced form of the pteridine cofactor. Because hydroxylation of tyrosine to dopa and of tryptophan to 5-hydroxytryptophan may require the same cofactor and pterin reductase as phenylalanine hydroxylase, these mutants may also prove useful for the study of the role of catecholamines and serotonin, substances known to be present in Tetrahymena.

UI	MeSH Term	Description	Entries
D009154	Mutation	Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.	Mutations
D010651	Phenylalanine Hydroxylase	An enzyme of the oxidoreductase class that catalyzes the formation of L-TYROSINE, dihydrobiopterin, and water from L-PHENYLALANINE, tetrahydrobiopterin, and oxygen. Deficiency of this enzyme may cause PHENYLKETONURIAS and PHENYLKETONURIA, MATERNAL. EC 1.14.16.1.	Phenylalanine 4-Hydroxylase,Phenylalanine 4-Monooxygenase,4-Hydroxylase, Phenylalanine,4-Monooxygenase, Phenylalanine,Hydroxylase, Phenylalanine,Phenylalanine 4 Hydroxylase,Phenylalanine 4 Monooxygenase
D010661	Phenylketonurias	A group of autosomal recessive disorders marked by a deficiency of the hepatic enzyme PHENYLALANINE HYDROXYLASE or less frequently by reduced activity of DIHYDROPTERIDINE REDUCTASE (i.e., atypical phenylketonuria). Classical phenylketonuria is caused by a severe deficiency of phenylalanine hydroxylase and presents in infancy with developmental delay; SEIZURES; skin HYPOPIGMENTATION; ECZEMA; and demyelination in the central nervous system. (From Adams et al., Principles of Neurology, 6th ed, p952).	Biopterin Deficiency,Dihydropteridine Reductase Deficiency Disease,Hyperphenylalaninemia, Non-Phenylketonuric,Phenylalanine Hydroxylase Deficiency Disease,BH4 Deficiency,DHPR Deficiency,Deficiency Disease, Dihydropteridine Reductase,Deficiency Disease, Phenylalanine Hydroxylase,Deficiency Disease, Phenylalanine Hydroxylase, Severe,Dihydropteridine Reductase Deficiency,Folling Disease,Folling's Disease,HPABH4C,Hyperphenylalaninaemia,Hyperphenylalaninemia Caused by a Defect in Biopterin Metabolism,Hyperphenylalaninemia, BH4-Deficient, C,Hyperphenylalaninemia, Tetrahydrobiopterin-Deficient, Due To DHPR Deficiency,Non-Phenylketonuric Hyperphenylalaninemia,Oligophrenia Phenylpyruvica,PAH Deficiency,PKU, Atypical,Phenylalanine Hydroxylase Deficiency,Phenylalanine Hydroxylase Deficiency Disease, Severe,Phenylketonuria,Phenylketonuria I,Phenylketonuria II,Phenylketonuria Type 2,Phenylketonuria, Atypical,Phenylketonuria, Classical,QDPR Deficiency,Quinoid Dihydropteridine Reductase Deficiency,Tetrahydrobiopterin Deficiency,Atypical PKU,Atypical Phenylketonuria,Biopterin Deficiencies,Classical Phenylketonuria,Deficiency, BH4,Deficiency, Biopterin,Deficiency, DHPR,Deficiency, Dihydropteridine Reductase,Deficiency, PAH,Deficiency, Phenylalanine Hydroxylase,Deficiency, QDPR,Deficiency, Tetrahydrobiopterin,Disease, Folling,Disease, Folling's,Hyperphenylalaninemia, Non Phenylketonuric,Non Phenylketonuric Hyperphenylalaninemia,Non-Phenylketonuric Hyperphenylalaninemias
D011621	Pteridines	Compounds based on pyrazino[2,3-d]pyrimidine which is a pyrimidine fused to a pyrazine, containing four NITROGEN atoms.	1,3,5,8-Tetraazanaphthalene,Pteridine,Pteridinone,Pyrazino(2,3-d)pyrimidine,Pyrazinopyrimidine,Pyrazinopyrimidines,Pyrimido(4,5-b)pyrazine,Pteridinones
D004195	Disease Models, Animal	Naturally-occurring or experimentally-induced animal diseases with pathological processes analogous to human diseases.	Animal Disease Model,Animal Disease Models,Disease Model, Animal
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D013768	Tetrahymena	A genus of ciliate protozoa commonly used in genetic, cytological, and other research.	Tetrahymenas