Creative Math of RNA Polymerase III Termination: Sense Plus Antisense Makes More Sense  Irina Artsimovitch, Georgi A. Belogurov  Molecular Cell  Volume 58, Issue 6, Pages 974-976 (June 2015) DOI: 10.1016/j.molcel.2015.06.003 Copyright © 2015 Elsevier Inc. Terms and Conditions

Figure 1 Formation of the PTC (A) The T-track in the non-template strand and C37 are required for pausing and termination in the “correct,” proximal region, as shown by Arimbasseri and Maraia (2015). (B) The RNAP (gray oval) PTC is stabilized by interactions of the non-template DNA strand with C37 (orange) or by formation of the nascent RNA hairpin. (C) The proposed termination/reinitiation pathway. Following TFIIIB (green) and TFIIIC (not shown)-mediated recruitment, RNAPIII initiates at the start site (a bent arrow) and transcribes until it reaches the T-track. Domains of C11 (yellow), C37, and C53 (pink) extend toward the RNAP active site (a red dot). Interactions between the non-template T residues and C37 mediate pausing (at U4) and formation of a metastable PTC. Addition of subsequent UMP residues triggers further destabilization of the hybrid and RNA release. RNAP rebinds the promoter via interactions between C37 and TFIIIB, which remains associated with the promoter, whereas TFIIIC is dispensable for recycling on most genes. DNA wrapping could provide easy means for RNAP III handover. Alternatively, RNAPIII could slide back to the transcription start, only 100 nucleotides away on tRNA genes; however, the reported high occupancy of RNAPIII makes this scenario less likely (see Dieci et al., 2013 for a review). The conformation and occupancy of the transcribed DNA are yet unknown, as indicated by breaks therein. Molecular Cell 2015 58, 974-976DOI: (10.1016/j.molcel.2015.06.003) Copyright © 2015 Elsevier Inc. Terms and Conditions