Structure of four amplified DNA novel joints.
The structures of four novel joints present in the amplified DNA of a Syrian hamster cell line highly resistant to N-(phosphonacetyl)-L-aspartate were analyzed. Novel joints J1, J2, and J4 were formed by recombination between two regions of wild-type DNA, whereas joint J3 is the end point of an inverted duplication. A fraction of the J3 copies displays a cruciform structure in the purified genomic DNA. The formation of J1 and J2 apparently involved a simple breakage and joining of the two wild-type sequences, whereas extra nucleotides are present at the junction point of J3 and J4. The two regions of the wild-type DNA which have recombined to form J1, J2, and J4 show few sequence similarities, indicating that these joints probably resulted from nonhomologous recombination. AT-rich regions are present in the vicinity of the breakpoint for the four joints and eight of 10 crossover points could be associated with putative topoisomerase I cleavage sites. Our results indicate that different types of novel joints are present in the amplified DNA of this cell line, which was isolated after several steps of selection.
Legouy
E
E
Laboratoire d'Oncologie Moléculaire, Institut Gustave Roussy, Villejuif, France.
Fossar
N
N
Lhomond
G
G
Brison
O
O
D000818:Animals; D001221:Aspartate Carbamoyltransferase / Q000235:genetics; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D001482:Base Composition; D001483:Base Sequence; D002223:Carbamoyl-Phosphate Synthase (Glutamine-Hydrolyzing) / Q000235:genetics; D002460:Cell Line; D003001:Cloning, Molecular; D003434:Crossing Over, Genetic; D004247:DNA / Q000096:biosynthesis / Q000235:genetics*; D004080:Dihydroorotase / Q000235:genetics; D004351:Drug Resistance / Q000235:genetics; D005784:Gene Amplification; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000235:genetics; D009154:Mutation; D010746:Phosphonoacetic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D011995:Recombination, Genetic; D015183:Restriction Mapping
C033626:CAD trifunctional enzyme; D009097:Multienzyme Complexes; D001224:Aspartic Acid; C013195:sparfosic acid; D004247:DNA; D001221:Aspartate Carbamoyltransferase; D004080:Dihydroorotase; D002223:Carbamoyl-Phosphate Synthase (Glutamine-Hydrolyzing); D010746:Phosphonoacetic Acid