title: [Directed modification of the Tcr gene region of the plasmid pBR322 using complementary single-stranded DNA fragments carrying alkylating groups].
abstract: A method is suggested for chemical modification of preselected regions of plasmid DNA by complementary single-stranded restriction fragments of DNA (srf DNA), carrying alkylating reagents. The gene coding for tetracycline resistance of plasmid pBR322 was used as a target. Srf DNA was prepared by a partial digestion of a double-stranded EcoRI-BamHI restriction fragment (377 base pairs) from Tcr by E. coli exonuclease III. The residues of an alkylating reagent N,N,N'-tri(beta-chlorethyl)-N'-(p-formylphenyl) propylenediamine 1,3 (TFP) were attached covalently to 4-5% of sfr DNA bases. The alkylating derivative of the sfr DNA was hybridized with supercoiled pBR322 plasmid DNA. The hybridization conditions (37 degrees C, 40% formamide, 0,2 M NaCl, 0,1 M Tris-HCl pH 7,5, 0,001 M EDTA) under which the bases carrying TFP residues are not eliminated from the sfr DNA, and transforming activity of pBR322 DNA does not decrease were established. It was shown that about 20% of plasmid pBR322 molecules form D-loops with alkylating sfr DNA under these conditions. It was shown that sfr DNA, carrying TFP can alkylate the complementary region of plasmid DNA, forming cross-linked D-loops. A method for the site-directed mutagenesis of switching off the preselected genes or non-transcribed DNA functional regions (promotors, introns etc) integrated into plasmids of other vectors is suggested.
mesh_terms: D000478:Alkylation; D002846:Chromatography, Affinity; D004247:DNA / Q000235:genetics; D004262:DNA Restriction Enzymes; D004269:DNA, Bacterial / Q000235:genetics*; D004277:DNA, Single-Stranded / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics*; D005798:Genes, Bacterial; D006868:Hydrolysis; D009690:Nucleic Acid Conformation; D009693:Nucleic Acid Hybridization; D010957:Plasmids
chemical_list: D004269:DNA, Bacterial; D004277:DNA, Single-Stranded; D004247:DNA; D004262:DNA Restriction Enzymes
vernacular_title: Napravlennaia modifikatsiia uchastka gena Tcr plazmidy pBR322 s pomoshch'iu komplementarnykh odnotsepochechnykh fragmentov DNK, nesushchikh alkiliruiushchie gruppy.