title: Characterization of a polypyrimidine/polypurine tract in the promoter of the gene for chicken malic enzyme.
abstract: Starvation inhibits and refeeding stimulates transcription of the malic enzyme gene in chick liver. DNA between -320 and +72 base pairs (bp) is DNase I-hypersensitive in hepatic nuclei from fed but not starved chicks (Ma, X. J., and Goodridge, A. G. (1992) Nucleic Acids Res. 20, 4997-5002). A polypyrimidine/polypurine (PPY/PPU) tract lies within the DNase I-hypersensitive region. In hepatocytes transiently transfected with plasmids containing triiodothyronine response elements and a minimal promoter from the malic enzyme gene linked to the chloramphenicol acetyltransferase gene, deletion of the PPY/PPU tract inhibited chloramphenicol acetyltransferase activity by about 90% with or without triiodothyronine. Fine mapping of S1 nuclease-sensitive sites suggests that the PPY/PPU tract can assume different isoforms of non-B-DNA, some of which may be triplex structures. The PPY/PPU tract contains specific binding sites for single- and double-stranded DNA binding proteins and, with 8 bp 3' of the tract, can function as a promoter. A (CT)7 repeat binds single-stranded DNA-binding protein and is essential for promoter activity. Two C-rich elements bind single-stranded DNA-binding proteins and may mediate inhibition of promoter function. The single- and double-stranded DNA-binding proteins that interact with the PPY/PPU tract may regulate transcription of the malic enzyme gene.
authors.affiliation: Department of Biochemistry, University of Iowa, Iowa City, Iowa 52240, USA.
authors.forename: G
authors.initials: G
authors.lastname: Xu
authors.forename: A G
authors.initials: AG
authors.lastname: Goodridge
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002642:Chick Embryo; D002645:Chickens / Q000235:genetics*; D015500:Chloramphenicol O-Acetyltransferase / Q000096:biosynthesis; D003850:Deoxyribonuclease I; D004435:Eating; D005215:Fasting; D015971:Gene Expression Regulation, Enzymologic; D008099:Liver / Q000201:enzymology*; D008291:Malate Dehydrogenase / Q000096:biosynthesis* / Q000235:genetics*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins / Q000096:biosynthesis; D014158:Transcription, Genetic; D014162:Transfection; D001616:beta-Galactosidase / Q000096:biosynthesis
chemical_list: D009687:Nuclear Proteins; D009838:Oligodeoxyribonucleotides; D011994:Recombinant Proteins; D008291:Malate Dehydrogenase; C034544:D-malate dehydrogenase (decarboxylating); D015500:Chloramphenicol O-Acetyltransferase; D003850:Deoxyribonuclease I; D001616:beta-Galactosidase