Transfer RNA genes are genomic targets for de novo transposition of the yeast retrotransposon Ty3
1990
Chalker, D.L. | Sandmeyer, S.B.
Insertions of the yeast element Ty3 resulting frominduced retrotransposition were characterized in order to identify thegenomic targets of transposition. The DNA sequences of the junctionsbetween Ty3 and flanking DNA were determined for two insertions of anunmarked element. Each insertion was at position -17 from the 5' end of a tRNA-coding sequence. Ninety-one independent insertions of a marked Ty3 element were studied by Southern blot analysis.Pairs of independent insertions into seven genomic loci accounted for 14 of these insertions. The DNAsequence flanking the insertion site was determined for at least one member of each pair ofintegrated elements. In each case, insertion was at position -16 or -17 relative to the 5' end of oneof seven different tRNA genes. This proportion of genomic loci used twice for Ty3 integration is consistent with that predicted by a Poissoon distribution for a number of genomic targets roughlyequivalent to the estimated number of yeast tRNA genes. In addition, insertions upstream of the same tRNAgene in one case were at different positions, but in all cases were in the same orientation.Thus, genomic insertions of Ty3 in a particular orientation are apparently specified by the target,while the actual position of the insertion relative to the tRNA-coding sequence can vary slightly.
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