Figure 8.
Model for noncanonical termination of RNAPIII. Nab2 accompanies RNAPIII on tDNA chromatin. When canonical termination occurs, the transcript is released and RNAPIII initiates another transcription cycle. When terminator read-through occurs, Nab2 targets the 3′ extended pre-tRNAs for degradation. Pre-tRNAs can be endonucleolytically cleaved by RNase Z (Trz1). Released tRNA extensions may be degraded by Rat1 and/or Mtr4 acting with the exosome or may be potentially processed to functional ncRNAs.
