Sequence, organization, and evolution of the A+T region of Drosophila melanogaster mitochondrial DNA.
The long (4.6-kb) A+T region of Drosophila melanogaster mitochondrial DNA has been cloned and sequenced. The A+T region is organized in two large arrays of tandemly repeated DNA sequence elements, with nonrepetitive intervening and flanking sequences comprising only 22% of its length. The first repeat array consists of five repeats of 338-373 bp. The second consists of four intact 464-bp repeats and a fifth partial repeat of 137 bp. Three DNA sequence elements are found to be highly conserved in D. melanogaster and in several Drosophila species with short A+T regions. These include a 300-bp DNA sequence element that overlaps the DNA replication origin and two thymidylate stretches identified on opposite DNA strands. We conclude that the length heterogeneity observed in the A+T regulatory region in mitochondrial DNAs from the genus Drosophila results from the expansion (and contraction) of the number of repeated DNA sequence elements. We also propose that the 300-bp conserved DNA sequence element, in conjunction with another primary sequence determinant, perhaps the adjacent thymidylate stretch, functions in the regulation of mitochondrial DNA replication.
Lewis
D L
DL
Department of Biochemistry, Michigan State University, East Lansing 48824-1319.
Farr
C L
CL
Farquhar
A L
AL
Kaguni
L S
LS
D000818:Animals; D001482:Base Composition; D001483:Base Sequence; D005075:Biological Evolution; D003001:Cloning, Molecular; D017124:Conserved Sequence; D004272:DNA, Mitochondrial / Q000737:chemistry / Q000235:genetics*; D004331:Drosophila melanogaster / Q000235:genetics*; D008969:Molecular Sequence Data; D012091:Repetitive Sequences, Nucleic Acid; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid
D004272:DNA, Mitochondrial