title: A knotted free minicircle in kinetoplast DNA.
abstract: Kinetoplast DNA, the mitochondrial DNA of trypanosomes, is a network containing thousands of minicircles that are topologically interlocked. The minicircle replication intermediates are free molecules that have been released from the network. We report here that one form of free minicircles is a trefoil knot. Identification of this knotted structure is based on its electrophoretic and sedimentation properties, its response to treatments with restriction enzymes or topoisomerase II, and its appearance by electron microscopy. Except for its topology, the knotted minicircle closely resembles a previously described replication intermediate with a unique gap in the newly synthesized L strand.
authors.affiliation: Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
authors.forename: K A
authors.initials: KA
authors.lastname: Ryan
authors.forename: T A
authors.initials: TA
authors.lastname: Shapiro
authors.forename: C A
authors.initials: CA
authors.lastname: Rauch
authors.forename: J D
authors.initials: JD
authors.lastname: Griffith
authors.forename: P T
authors.initials: PT
authors.lastname: Englund
mesh_terms: D000818:Animals; D002874:Chromosome Mapping; D004261:DNA Replication; D004250:DNA Topoisomerases, Type II / Q000494:pharmacology; D004272:DNA, Mitochondrial; D004587:Electrophoresis, Agar Gel; D008854:Microscopy, Electron; D009693:Nucleic Acid Hybridization; D014345:Trypanosoma / Q000235:genetics*
chemical_list: D004272:DNA, Mitochondrial; D004250:DNA Topoisomerases, Type II