The human RNA polymerase I structure reveals an HMG-like transcription factor docking domain specific to metazoans

Daiss, J. L.; Pilsl, M.; Straub, K.; Bleckmann, A.; Höcherl, M.; Heiss, F. B.; Abascal-Palacios, G.; Ramsay, E.; Tluckova, K.; Mars, J.-C.; Bruckmann, A.; Bernecky, C.; Lamour, V.; Panov, K.; Vannini, A.; Moss, T.; Engel, C.

doi:10.1101/2021.12.22.473891

bioRxiv · 10.1101/2021.12.22.473891

The human RNA polymerase I structure reveals an HMG-like transcription factor docking domain specific to metazoans

Daiss, J. L.·Pilsl, M.·Straub, K.·Bleckmann, A.·Höcherl, M.·Heiss, F. B.·Abascal-Palacios, G.·Ramsay, E.·Tluckova, K.·Mars, J.-C.·Bruckmann, A.·Bernecky, C.·Lamour, V.·Panov, K.·Vannini, A.·Moss, T.·Engel, C.

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Abstract

Transcription of the ribosomal RNA precursor by RNA polymerase (Pol) I is a major determinant of cellular growth and dysregulation is observed in many cancer types. Here, we present the purification of human Pol I from cells carrying a genomic GFP-fusion on the largest subunit allowing the structural and functional analysis of the enzyme across species. In contrast to yeast, human Pol I carries a single-subunit stalk and in vitro transcription indicates a reduced proofreading activity. Determination of the human Pol I cryo-EM reconstruction in a close-to-native state rationalizes the effects of disease-associated mutations and uncovers an additional domain that is built into the sequence of Pol I subunit RPA1. This dock II domain resembles a truncated HMG-box incapable of DNA-binding which may serve as a downstream-transcription factor binding platform in metazoans. Biochemical analysis and ChIP data indicate that Topoisomerase 2a can be recruited to Pol I via the domain and cooperates with the HMG-box domain containing factor UBF. These adaptations of the metazoan Pol I transcription system may allow efficient release of positive DNA supercoils accumulating downstream of the transcription bubble.

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Daiss, J. L., Pilsl, M., Straub, K., Bleckmann, A., Höcherl, M., Heiss, F. B., Abascal-Palacios, G., Ramsay, E., Tluckova, K., Mars, J.-C., Bruckmann, A., Bernecky, C., Lamour, V., Panov, K., Vannini, A., Moss, T., Engel, C.. 2021-12-22. The human RNA polymerase I structure reveals an HMG-like transcription factor docking domain specific to metazoans. https://doi.org/10.1101/2021.12.22.473891

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