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Single-Cell Biophysics: Measurement, Modulation, and Modeling
Sunday Speaker Abstracts
20
Bacterial Transcription Meets Chromosome Organization: A Single-Molecule Perspective
Achillefs Kapanidis
, Mathew Stracy.
University of Oxford, Oxford, United Kingdom.
Despite the fundamental importance of transcription, a comprehensive analysis of RNA
polymerase behavior and its role in the nucleoid organization in vivo is lacking, in part due to
lack of sensitivity of conventional imaging and to its inability to resolve fine cellular structures.
To address this challenge, my group is using superresolution fluorescence microscopy to study
the localization and dynamics of the transcription machinery and the bacterial chromosome in
live bacterial cells, both at the single-molecule and the population level.
Specifically, we use photo-activated single-molecule tracking to discriminate between diffusing
RNA polymerases and RNA polymerases specifically bound to DNA, either on promoters or
transcribed genes. We find that transcription can cause spatial reorganization of the nucleoid,
with movement of gene loci out of the bulk of DNA as levels of transcription increase. We also
studied the degree and mode of interaction of RNAP with the DNA during on the promoter
search process, showing that RNAP interacts substantially with non-specific DNA. Current work
focuses on identifying the identity and organisation of genes that are highly transcribed, as well
as on developing assays to study the non-specific interactions of DNA-binding proteins with
chromosomal DNA. Our work provides a global view of the organization of transcription and its
interplay with chromosome organisation in living bacteria.