title: Electron microscope heteroduplex mapping of naphthalene oxidation genes on the NAH7 and SAL1 plasmids.
abstract: Introduction of the transposon Tn5 to serve as a marker allows electron microscope heteroduplex mapping of the naphthalene oxidation genes on the approximately 83-kb NAH7 and the related approximately 85-kb SAL1 plasmids. The electron microscope-mapped gene positions on the NAH7 plasmid are in close agreement with those mapped previously by restriction digestion. The SAL1 plasmid can be considered as a mutant NAH7 plasmid which fails to direct the conversion of naphthalene to salicylate because of a mutational block but retains intact coding sequences for salicylate oxidation. Analysis of heteroduplex molecules formed between the SAL1 and NAH7::Tn5 EcoRI fragments and the known NAH7/SAL1 homology strongly suggest that the SAL1 DNA is completely homologous to NAH7 DNA except that a approximately 2.5-kb DNA segment constituting most of the nahA gene is replaced by approximately 4.6-kb nonhomologous DNA.
mesh_terms: D002874:Chromosome Mapping; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000235:genetics; D005798:Genes, Bacterial; D008854:Microscopy, Electron; D009281:Naphthalenes / Q000378:metabolism*; D009692:Nucleic Acid Heteroduplexes / Q000235:genetics*; D010084:Oxidation-Reduction; D010957:Plasmids; D011549:Pseudomonas / Q000235:genetics* / Q000378:metabolism
chemical_list: D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D009281:Naphthalenes; D009692:Nucleic Acid Heteroduplexes