Role of RNA polymerase III transcription factors in the selection of integration sites by the dictyostelium non-long terminal repeat retrotransposon TRE5-A.
In the compact Dictyostelium discoideum genome, non-long terminal repeat (non-LTR) retrotransposons known as TREs avoid accidental integration-mediated gene disruption by targeting the vicinity of tRNA genes. In this study we provide the first evidence that proteins of a non-LTR retrotransposon interact with a target-specific transcription factor to direct its integration. We applied an in vivo selection system that allows for the isolation of natural TRE5-A integrations into a known genomic location upstream of tRNA genes. TRE5-A frequently modified the integration site in a way characteristic of other non-LTR retrotransposons by adding nontemplated extra nucleotides and generating small and extended target site deletions. Mutations within the B-box promoter of the targeted tRNA genes interfered with both the in vitro binding of RNA polymerase III transcription factor TFIIIC and the ability of TRE5-A to target these genes. An isolated B box was sufficient to enhance TRE5-A integration in the absence of a surrounding tRNA gene. The RNA polymerase III-transcribed ribosomal 5S gene recruits TFIIIC in a B-box-independent manner, yet it was readily targeted by TRE5-A in our assay. These results suggest a direct role of an RNA polymerase III transcription factor in the targeting process.
Siol
Oliver
O
Institut für Pharmazeutische Biologie, Universität Frankfurt/M., Frankfurt, Germany.
Boutliliss
Moustapha
M
Chung
Thanh
T
Glöckner
Gernot
G
Dingermann
Theodor
T
Winckler
Thomas
T
D000818:Animals; D001483:Base Sequence; D004023:Dictyostelium / Q000201:enzymology / Q000235:genetics*; D015966:Gene Expression Regulation, Fungal; D008969:Molecular Sequence Data; D009154:Mutation; D012320:RNA Polymerase III / Q000235:genetics*; D012343:RNA, Transfer / Q000235:genetics; D018626:Retroelements / Q000235:genetics*; D017422:Sequence Analysis, DNA / Q000379:methods; D020079:Terminal Repeat Sequences; D014157:Transcription Factors / Q000235:genetics*; D014158:Transcription, Genetic
D018626:Retroelements; D014157:Transcription Factors; D012343:RNA, Transfer; D012320:RNA Polymerase III