Detainment of Tam3 Transposase at Plasma Membrane by Its BED-Zinc Finger Domain

Transposable elements (TEs) are considered to be parasites of host genomes because they act as powerful mutagens. If not kept in check, they can cause gene disruption, genome rearrangement, and genomic takeover. Hence, activities of TEs are under the rigid control of hosts. To date, all identified TE regulations have been epigenetic dependent, with the exception of the DNA transposon Tam3. Blocking nuclear translocation of Tam3 transposase (TPase) is consistent with the suppression of Tam3 in Antirrhinum majus. In this article, we discovered that epigenetic-independent regulation of Tam3 is mediated by the BED-zinc finger (Znf-BED) domain of Tam3 TPase. The host targets the N terminus of the Znf-BED domain, which contains two highly conserved aromatic amino acids, to detain Tam3 TPase at the plasma membrane and to silence Tam3. Zinc finger proteins perform broader functions in transcriptional regulation through their DNA binding ability. Our data revealed that the posttranslational epigenetic-independent silencing against TEs was a result of the protein binding ability of the Znf-BED domain.