Biophysical Society Thematic Meeting| Lima 2019

Revisiting the Central Dogma of Molecular Biology at the Single-Molecule Level

Poster Abstracts

22-POS Board 22 IN SINGULO STUDY OF THE MODULATION OF TRANSCRIPTION ELONGATION OF MTBRNAP BY MTBGREA Omar C Herrera-asmat 1 ; Wenxia Lin 2,4 ; Daniel G Guerra-Guiraldez 1 ; Carlos J Bustamante 1,2,3 ; 1 Universidad Peruana Cayetano Heredia, Laboratorio de Moléculas Individuales, Facultad de Ciencias y Filosofía, Lima, Peru 2 California Institute for Quantitative Biosciences, QB3, University of California, , Berkeley, CA, USA 3 University of California, Department of Molecular and Cell Biology, Department of Physics and Department of Chemistry, Berkeley, CA, USA 4 Shenzhen University, Department of Biomedical Engineering, Shenzhen, China RNA polymerase of Mycobacterium tuberculosis (MtbRNAP) is a target of antibiotics to treat Tuberculosis. While recently structural approaches have provided new insights into the transcription mechanism in Mtb, wherein transcriptional factors play a key role during elongation, functional biophysical studies of this central enzyme have lagged behind. MtbGreA, a transcription factor known to reduce backtracking events, is thought to play a role in both initiation and elongation, while MtbCarD, another essential factor, has been proposed to be involved only in initiation and in early elongation stages. We present the first single molecule trajectories of Mtb RNAP using high resolution optical tweezers, and investigate the effect of MtbGreA on MtbCarD during transcription elongation. We found that MtbGreA reduces the pause-free velocity (17.2 ±0.3 bp/sec versus 21.5 ± 0.3 bp/sec) and decreases both the frequency and duration of pauses of the enzyme. In contrast, Mtb CarD increases the duration and density of transcriptional pauses, but this effect is abolished by MtbGreA. A model to rationalize these observations is presented.

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