Fig. 6: General comparison of TFIIIB targeting by RNA Polymerase III and Ty3 intasome.

Comparison of RNA Polymerase III and Ty3 intasome recruitment by TFIIIB transcription factor. TFIIIB subunits are depicted as ribbons and coloured as described in Fig. 2. S. cerevisiae models of RNA Pol III pre-initiation complex (RNA Pol III PIC, PDB code: 6EU0) and Ty3 strand-transfer complex bound to TFIIIB (Ty3 STC, this work) were superimposed onto TBP subunit of TFIIIB. RNA Pol III and Ty3 intasome are depicted as wheat and grey molecular surfaces, and their boundaries are highlighted with brown and black lines, respectively. Binding of both enzymatic machineries to RNA Pol III-transcribed genes requires equivalent regions, which prevents simultaneous RNA transcription and integration events. Models of the target DNA are shown as ribbon and coloured as described in Fig. 2. Whereas the orientation of the upstream DNA is conserved, the direction of the tDNA in the proximity of the TSS differs upon binding of the two enzymes.