Two subfamilies of MDG1 retrotransposon with different evolutionary histories in D. melanogaster

Two copies of nonmobile retrotransposon localized in D. melanogaster heterochromatin (mdg1het) were sequenced at the 3'-end. The comparison of 2.5-kb mdg1het sequences with the sequence of cognate euchomatic transposable copies (mdg1tr) revealed an intact mdg1 ORF2 encoding pol gene in mdg1het,...

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Bibliographic Details
Published in:Journal of molecular evolution 1993-11, Vol.37 (5), p.496-503
Main Author: Nurminsky, D.I
Format: Article
Language:English
Subjects:
Animals
Base Sequence
Biological Evolution
CODE GENETIQUE
CODIGO GENETICO
DNA Transposable Elements - genetics
DROSOPHILA MELANOGASTER
Drosophila melanogaster - genetics
EVOLUCION
EVOLUTION
Gene Rearrangement
GENETICA
GENETIQUE
Heterochromatin - ultrastructure
Models, Genetic
Molecular Sequence Data
Point Mutation
Recombination, Genetic
Restriction Mapping
SECUENCIA NUCLEICA
Sequence Homology, Nucleic Acid
SEQUENCE NUCLEIQUE
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Summary:Two copies of nonmobile retrotransposon localized in D. melanogaster heterochromatin (mdg1het) were sequenced at the 3'-end. The comparison of 2.5-kb mdg1het sequences with the sequence of cognate euchomatic transposable copies (mdg1tr) revealed an intact mdg1 ORF2 encoding pol gene in mdg1het, and two-thirds of nucleotide substitutions in this ORF were synonymous. All the known mdg regulatory elements in the mdg1het LTR also are conserved, in spite of numerous deletions and nucleotide substitutions elsewhere in this region. These data suggest that the mdg1het subfamily lost its mobility more recently than other functions were lost. The G leads to A hypermutation known to occur in the reverse transcription cycle of retroviruses was detected in one mdg1het copy. The structure of the enchancerlike region in mdg1het suggests a reduced transcription level and, therefore, transposition frequency, relative to mdg1tr. The number of nucleotide substitutions suggests that the time of mdg1het mobility loss was less than 0.3-0.5 Myr ago
ISSN:0022-2844
1432-1432
DOI:10.1007/BF00160430