Structural basis of TFIIIC-dependent RNA polymerase III transcription initiation.

Anna Talyzina, Yan Han, Chiranjib Banerjee, Susan Fishbain, Alexis Reyes, Reza Vafabakhsh, Yuan He

Molecular cell 2023 Aug 03

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RNA polymerase III (Pol III) is responsible for transcribing 5S ribosomal RNA (5S rRNA), tRNAs, and other short non-coding RNAs. Its recruitment to the 5S rRNA promoter requires transcription factors TFIIIA, TFIIIC, and TFIIIB. Here, we use cryoelectron microscopy (cryo-EM) to visualize the S. cerevisiae complex of TFIIIA and TFIIIC bound to the promoter. Gene-specific factor TFIIIA interacts with DNA and acts as an adaptor for TFIIIC-promoter interactions. We also visualize DNA binding of TFIIIB subunits, Brf1 and TBP (TATA-box binding protein), which results in the full-length 5S rRNA gene wrapping around the complex. Our smFRET study reveals that the DNA within the complex undergoes both sharp bending and partial dissociation on a slow timescale, consistent with the model predicted from our cryo-EM results. Our findings provide new insights into the transcription initiation complex assembly on the 5S rRNA promoter and allow us to directly compare Pol III and Pol II transcription adaptations. Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.

Citation

Anna Talyzina, Yan Han, Chiranjib Banerjee, Susan Fishbain, Alexis Reyes, Reza Vafabakhsh, Yuan He. Structural basis of TFIIIC-dependent RNA polymerase III transcription initiation. Molecular cell. 2023 Aug 03;83(15):2641-2652.e7