7FJI

human Pol III elongation complex

Summary for 7FJI

• Entry DOI: 10.2210/pdb7fji/pdb
• EMDB information: 31621
• Descriptor: DNA-directed RNA polymerase III subunit RPC1, DNA-directed RNA polymerases I, II, and III subunit RPABC5, DNA-directed RNA polymerases I and III subunit RPAC2, ... (22 entities in total)
• Functional Keywords: rna polymerase iii, elongation, pre-termination, transcription, transcription-rna-dna complex, transcription/rna/dna
• Biological source: Homo sapiens (Human); More
• Total number of polymer chains: 20
• Total formula weight: 745497.27

Authors

Hou, H.,Xu, Y. (deposition date: 2021-08-04, release date: 2021-10-27, Last modification date: 2024-11-13)

Primary citation

Hou, H.,Li, Y.,Wang, M.,Liu, A.,Yu, Z.,Chen, K.,Zhao, D.,Xu, Y.
Structural insights into RNA polymerase III-mediated transcription termination through trapping poly-deoxythymidine.
Nat Commun, 12:6135-6135, 2021

PubMed Abstract: Termination of the RNA polymerase III (Pol III)-mediated transcription requires the conversion of an elongation complex (EC) to a pre-termination complex (PTC) on poly-deoxythymidine (dT)-containing non-template strand, a mechanism distinct from Pol I and Pol II. Here, our in vitro transcription elongation assay showed that 5-7 dT-containing DNA template led to transcription termination of Pol III, but not Pol I or Pol II. We assembled human Pol III PTC on a 7 dT-containing DNA template and determined the structure at 3.6 Å resolution. The structure reveals that poly-dT are trapped in a narrow exit tunnel formed by RPC2. A hydrophobic gate of the exit tunnel separates the bases of two connected deoxythymidines and may prevent translocation of the non-template strand. The fork loop 2 stabilizes both template and non-template strands around the transcription fork, and may further prevent strand translocation. Our study shows that the Pol III-specific exit tunnel and FL2 allow for efficient translocation of non-poly-dT sequence during transcription elongation but trap poly-dT to promote DNA retention of Pol III, revealing molecular mechanism of poly-dT-dependent transcription termination of Pol III.

PubMed: 34675218
DOI: 10.1038/s41467-021-26402-9

Experimental method

ELECTRON MICROSCOPY (3.6 Å)