title: Instability of regions containing expanded CAG repeats during replication in Escherichia coli probed by labeled oligonucleotides.
abstract: The instability of plasmid DNAs that contained various numbers of repeated CAG units in Escherichia coli was examined. Synthetic [5'-32P](CAG)15 and [5'-32P]-(CTG)15 oligonucleotides were incubated with plasmid DNA. A minor fraction of the plasmid DNA formed a stable complex with either the repeated CAG or the repeated CTG oligonucleotide when the number of CAG repeats in the plasmid DNA was more than 30, regardless of the polarity of replication. The formation of the complexes appeared to occur by the normal hybridization process. The DNA that formed stable complexes could be purified with a biotinylated fragments of CAG repeats and avidin-coated beads. In addition, in the case of the DNA containing CAG repeats derived from the IT15 gene of a patient with Huntington's disease, there seemed to be an unusual product that contained a partially replicated product that extended only from the origin of replication to the CAG-repeated region. The formation of this product was observed when replication started downstream of IT15 gene.
authors.affiliation: Institute for Comprehensive Medical Science, Fujita Health University, Aichi, Japan.
authors.forename: W
authors.initials: W
authors.lastname: Ito
authors.forename: J
authors.initials: J
authors.lastname: Goto
authors.forename: I
authors.initials: I
authors.lastname: Kanazawa
authors.forename: Y
authors.initials: Y
authors.lastname: Kurosawa
mesh_terms: D001483:Base Sequence; D002460:Cell Line; D004261:DNA Replication; D004926:Escherichia coli / Q000235:genetics*; D006801:Humans; D000071058:Huntingtin Protein; D006816:Huntington Disease / Q000235:genetics; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D015345:Oligonucleotide Probes; D010957:Plasmids; D011506:Proteins / Q000235:genetics; D015183:Restriction Mapping; D018911:Trinucleotide Repeats
chemical_list: C086055:HTT protein, human; D000071058:Huntingtin Protein; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D015345:Oligonucleotide Probes; D011506:Proteins