title: [Dependence of the activity of phi X 174 B-promoter in the expression of Escherichia coli gal-operon on the number of its copies and their orientation].
abstract: Promoter activities of different restriction fragments of the R8 DNA region of phage phi X 174 were compared. The studied DNA fragments included HindII fragment R8 (B-promoter), its left portion 49 nucleotide long, and the central segment containing 113 nucleotides generated by AluI. The promoter activity of these fragments was quantitated by the appearance of uridyltransferase and galactokinase activities in Escherichia coli clones carrying plasmids pHD68-17. The gal-promoters of these plasmids was substituted for the three aforementioned restriction fragments. The R8 region and its central part (BII-promoter) had comparable promoter activities while the left part containing the putative BI-promoter, did not induce clones with the expressed gal-operon. Clones containing 1, 2, 3 copies of the promoter fragment R8 were selected. No clones were revealed with more copies. All selected di- and tri-promoter clusters in plasmids had the same correct orientation of all inserted promoters with respect to the gal-operon. The expression of the gal-operon in E. coli was nearly directly proportional to the number of the phi X 174 B-promoters inserted before the operon.
mesh_terms: D010584:Bacteriophage phi X 174 / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D004262:DNA Restriction Enzymes; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D005686:Galactokinase / Q000235:genetics; D005786:Gene Expression Regulation; D009876:Operon; D006599:UDPglucose-Hexose-1-Phosphate Uridylyltransferase / Q000235:genetics
chemical_list: D005686:Galactokinase; D006599:UDPglucose-Hexose-1-Phosphate Uridylyltransferase; D004262:DNA Restriction Enzymes
vernacular_title: Zavisimost' aktivnosti B-promotora bakteriofaga phiX174 v ékspressii gal-operona Escherichia coli ot chisla ego kopiĭ i ikh orientatsii.