title: Mechanism of acquisition of chromosomal markers by plasmids in Haemophilus influenzae.
abstract: The hybrid plasmid pNov1 readily acquired genetic information from the chromosome of wild-type, but not rec-2, cells. Most of the recombination had taken place 1 h after entrance of the plasmid into the cell, as judged by transformation of rec-2 by lysates made from wild-type cells exposed to pNov1. Measurement of physical transfer from radioactively labeled cellular DNA to plasmids recombining in wild-type cells failed, since there was little more radioactivity in plasmids from such cells than from labeled rec-2 recipients, in which no recombination took place. EcoRI digestion of pNov1 divided the DNA into a 1.7-kilobase-pair fragment containing the novobiocin resistance marker and a 13-kilobase-pair fragment containing all of the original vector and considerable portions homologous to the chromosome. Transformation by the large fragment alone resulted in a plasmid the size of the original pNov1. Our hypothesis to explain the data is that genetic transfer from chromosome to plasmid took place by a copy choice mechanism.
mesh_terms: D001483:Base Sequence; D002876:Chromosomes, Bacterial / Q000502:physiology*; D004262:DNA Restriction Enzymes; D005819:Genetic Markers; D006193:Haemophilus influenzae / Q000187:drug effects / Q000235:genetics*; D009675:Novobiocin / Q000494:pharmacology; D010957:Plasmids; D013045:Species Specificity; D013307:Streptomycin / Q000494:pharmacology; D014169:Transformation, Bacterial
chemical_list: D005819:Genetic Markers; D009675:Novobiocin; D004262:DNA Restriction Enzymes; D013307:Streptomycin