title: The C-module-binding factor supports amplification of TRE5-A retrotransposons in the Dictyostelium discoideum genome.
abstract: Retrotransposable elements are molecular parasites that have invaded the genomes of virtually all organisms. Although retrotransposons encode essential proteins to mediate their amplification, they also require assistance by host cell-encoded machineries that perform functions such as DNA transcription and repair. The retrotransposon TRE5-A of the social amoeba Dictyostelium discoideum generates a notable amount of both sense and antisense RNAs, which are generated from element-internal promoters, located in the A module and the C module, respectively. We observed that TRE5-A retrotransposons depend on the C-module-binding factor (CbfA) to maintain high steady-state levels of TRE5-A transcripts and that CbfA supports the retrotransposition activity of TRE5-A elements. The carboxy-terminal domain of CbfA was found to be required and sufficient to mediate the accumulation of TRE5-A transcripts, but it did not support productive retrotransposition of TRE5-A. This result suggests different roles for CbfA protein domains in the regulation of TRE5-A retrotransposition frequency in D. discoideum cells. Although CbfA binds to the C module in vitro, the factor regulates neither C-module nor A-module promoter activity in vivo. We speculate that CbfA supports the amplification of TRE5-A retrotransposons by suppressing the expression of an as yet unidentified component of the cellular posttranscriptional gene silencing machinery.
authors.affiliation: School of Biology and Pharmacy, Institute of Pharmacy, Department of Pharmaceutical Biology, University of Jena, Semmelweisstrasse 10, 07743 Jena, Germany.
authors.forename: Annika
authors.initials: A
authors.lastname: Bilzer
authors.forename: Heike
authors.initials: H
authors.lastname: Dölz
authors.forename: Alexander
authors.initials: A
authors.lastname: Reinhardt
authors.forename: Anika
authors.initials: A
authors.lastname: Schmith
authors.forename: Oliver
authors.initials: O
authors.lastname: Siol
authors.forename: Thomas
authors.initials: T
authors.lastname: Winckler
mesh_terms: D004268:DNA-Binding Proteins / Q000494:pharmacology / Q000502:physiology*; D004023:Dictyostelium / Q000235:genetics*; D017930:Genes, Reporter; D011401:Promoter Regions, Genetic; D015800:Protozoan Proteins / Q000494:pharmacology / Q000502:physiology*; D018626:Retroelements / Q000235:genetics*; D014158:Transcription, Genetic; D015533:Transcriptional Activation
chemical_list: D004268:DNA-Binding Proteins; D015800:Protozoan Proteins; D018626:Retroelements; C400205:cbfA protein, Dictyostelium discoideum