title: [Enhancement of expression of Escherichia coli uridine phosphorylase gene as a result of duplication].
abstract: The thymine-requiring (thy) Escherichia coli strains normally convert thymine to thymidine through the action of thymidine phosphorylase, an enzyme, whose synthesis is directed by tpp gene of the deo operon. Selection for efficient thymine utilization in the thy mutants carrying a deletion in the tpp gene allows to obtain clones with constitutive synthesis of an alternative enzyme, uridine phosphorylase coded by the udp gene. Such clones are usually formed, due to "promoter-up" constitutive udpP mutants. Further selection for increased expression of the udp gene was performed on the background of udpP1 and udpP18 "promoter-up" constitutive mutants isolated previously. Several lines of evidence obtained by using transposon insertions suggest that the increased synthesis of uridine phosphorylase in some newly isolated mutants is due to duplications of the udp gene. In two mutants the adjacent metE gene is involved in duplications simultaneously with the udp gene.
mesh_terms: D003001:Cloning, Molecular; D003434:Crossing Over, Genetic; D004742:Enhancer Elements, Genetic; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D005786:Gene Expression Regulation; D005798:Genes, Bacterial; D009154:Mutation; D010430:Pentosyltransferases / Q000235:genetics*; D011401:Promoter Regions, Genetic; D014543:Uridine Phosphorylase / Q000235:genetics*
chemical_list: D010430:Pentosyltransferases; D014543:Uridine Phosphorylase
vernacular_title: Usilenie ekspressii gena uridinfosforilazy (udp) Escherichia coli v rezul'tate duplikatsii.