SNAP output for PDB entry 8e74 [SNAP web server]

PDB-id

8e74; SNAP-derived features in text and JSON formats; DNAproDB

Class

transcription-DNA-RNA

Method

cryo-EM (2.94 Å)

Summary

Mycobacterium tuberculosis rnap paused elongation complex with nusg transcription factor

Reference

Delbeau M, Omollo EO, Froom R, Koh S, Mooney RA, Lilic M, Brewer JJ, Rock J, Darst SA, Campbell EA, Landick R (2023): "Structural and functional basis of the universal transcription factor NusG pro-pausing activity in Mycobacterium tuberculosis." Mol.Cell, 83, 1474-1488.e8. doi: 10.1016/j.molcel.2023.04.007.

Abstract

Transcriptional pauses mediate regulation of RNA biogenesis. DNA-encoded pause signals trigger pausing by stabilizing RNA polymerase (RNAP) swiveling and inhibiting DNA translocation. The N-terminal domain (NGN) of the only universal transcription factor, NusG/Spt5, modulates pausing through contacts to RNAP and DNA. Pro-pausing NusGs enhance pauses, whereas anti-pausing NusGs suppress pauses. Little is known about pausing and NusG in the human pathogen Mycobacterium tuberculosis (Mtb). We report that MtbNusG is pro-pausing. MtbNusG captures paused, swiveled RNAP by contacts to the RNAP protrusion and nontemplate-DNA wedged between the NGN and RNAP gate loop. In contrast, anti-pausing Escherichia coli (Eco) NGN contacts the MtbRNAP gate loop, inhibiting swiveling and pausing. Using CRISPR-mediated genetics, we show that pro-pausing NGN is required for mycobacterial fitness. Our results define an essential function of mycobacterial NusG and the structural basis of pro- versus anti-pausing NusG activity, with broad implications for the function of all NusG orthologs.