Reference: Baek I, et al. (2021) Single-molecule studies reveal branched pathways for activator-dependent assembly of RNA polymerase II pre-initiation complexes. Mol Cell 81(17):3576-3588.e6

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Abstract


RNA polymerase II (RNA Pol II) transcription reconstituted from purified factors suggests pre-initiation complexes (PICs) can assemble by sequential incorporation of factors at the TATA box. However, these basal transcription reactions are generally independent of activators and co-activators. To study PIC assembly under more realistic conditions, we used single-molecule microscopy to visualize factor dynamics during activator-dependent reactions in nuclear extracts. Surprisingly, RNA Pol II, TFIIF, and TFIIE can pre-assemble on enhancer-bound activators before loading into PICs, and multiple RNA Pol II complexes can bind simultaneously to create a localized cluster. Unlike TFIIF and TFIIE, TFIIH binding is singular and dependent on the basal promoter. Activator-tethered factors exhibit dwell times on the order of seconds. In contrast, PICs can persist on the order of minutes in the absence of nucleotide triphosphates, although TFIIE remains unexpectedly dynamic even after TFIIH incorporation. Our kinetic measurements lead to a new branched model for activator-dependent PIC assembly.

Reference Type
Journal Article | Research Support, N.I.H., Extramural | Research Support, Non-U.S. Gov't
Authors
Baek I, Friedman LJ, Gelles J, Buratowski S
Primary Lit For
General transcription factor TFIIF complex | General transcription factor complex TFIIE | General transcription factor TFIIH complex | DNA-directed RNA polymerase II complex
Additional Lit For
TFA2 | SSL2 | RPB9 | RPB7 | RPB4 | TFB1 | RPC10 | KIN28 | TFB5 | TFA1 | RPB5 | ... Show all