Biophysical Society Thematic Meeting| Lima 2019

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

Poster Abstracts

56-POS Board 56 SPATIAL ORGANIZATION OF RNA POLYMERASE AND ITS RELATIONSHIP WITH TRANSCRIPTION IN E. COLI Xiaoli Weng 1,2 ; Christopher H Bohrer 2 ; Kelsey Bettridge 2 ; Arvin C Lagda 3 ; Cedric Cagliero 4,5 ; Ding J Jin 4 ; Jie Xiao 2 ; 1 National Institutes of Health , Laboratory of Molecular Biology, CCR, Bethesda, MD, USA 2 Johns Hopkins University School of Medicine, Biophysics and Biophysical Chemistry, Baltimore, MD, USA 3 Icahn School of Medicine at Mount Sinai, Department of Microbiology, New York, NY, USA 4 National Cancer Institute at Frederick, RNA Biology Laboratory, Frederick, MD, USA 5 Jecho Laboratories Inc. , Frederick , MD, USA Recent studies have shown that RNA polymerase (RNAP) is organized into distinct clusters in E. coli and B. subtilis cells. Spatially organized molecular components in prokaryotic systems imply compartmentalization without the use of membranes, which may offer new insights into pertinent functions and regulations. It has been proposed that the formation of RNAP clusters is driven by active ribosomal RNA (rRNA) transcription and that RNAP clusters function as factories for highly efficient transcription. In this work, we examined these hypotheses by investigating the spatial organization and transcription activity of RNAP in E. coli cells using quantitative superresolution imaging coupled with genetic and biochemical assays. We observed that RNAP formed distinct clusters that were preferentially located in the center of the nucleoid and engaged in active rRNA synthesis under a rich medium growth condition. Surprisingly, a large fraction of RNAP clusters persisted under various conditions in which rRNA synthesis was reduced or abolished, and was only significantly diminished when all RNA transcription was inhibited globally. Moreover, the cellular distribution of RNAP closely followed the morphology of the underlying nucleoid under all conditions tested irrespective of the corresponding transcription activity. These results suggested that RNAP was organized into active transcription centers under the rich medium growth condition; their spatial arrangement at the cellular level, however, was not dependent on rRNA synthesis activity and was likely organized by the underlying nucleoid.

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