title: Structure of inserted bacteriophage Mu-1 DNA and physical mapping of bacterial genes by Mu-1 DNA insertion.
abstract: It is shown, by electron microscope observation of the structures of heteroduplexes, that Mu-1 DNA inserted into the bacterial episomes Flac and F(8)[1] is collinear with, rather than a circulation permutation of, the DNA of the mature Mu-1 bacteriophage. Observation of the position of the inserted Mu defines a point within the gene that has been inactivated (the lacI gene for Flac and a transfer gene in F(8)[1] in these particular instances). These examples illustrate a new, general method for physical gene mapping. The episome with Mu DNA inserted into F(8)[1] [i.e., F(8)[1](Mu)], although derived from a single colony, is heterogeneous in that a self-renatured sample shows a nonhomology loop of length 3.0 kb. This nonhomology loop, which has previously been observed in mature Mu-1 DNA, is due to an inversion.
mesh_terms: D002874:Chromosome Mapping; D002876:Chromosomes, Bacterial; D003090:Coliphages / Q000032:analysis*; D004277:DNA, Single-Stranded / Q000032:analysis; D004279:DNA, Viral / Q000032:analysis*; D004926:Escherichia coli; D005838:Genotype; D007785:Lactose / Q000096:biosynthesis; D008854:Microscopy, Electron; D008961:Models, Structural; D009690:Nucleic Acid Conformation; D009695:Nucleic Acid Renaturation; D009876:Operon
chemical_list: D004277:DNA, Single-Stranded; D004279:DNA, Viral; D007785:Lactose