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Distinct Spatial Organisation of Rho and RNA Polymerase in Salmonella Cells.
Lionello Bossi1, Romain Le Bars1, Johnathan C Black2
1Université Paris-Saclay, CEA, CNRS, Institut de Biologie Intégrative de la Cellule (I2BC), Gif-sur-Yvette, France.
Molecular Microbiology
|June 29, 2026
Summary
Bacterial Rho factor, an RNA translocase, and RNA polymerase (RNAP) spatially segregate within cells. This unexpected distribution suggests Rho performs functions beyond transcription termination.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Rho-dependent transcription termination is crucial for bacterial gene regulation.
- The spatial organization of Rho and RNA polymerase (RNAP) within bacterial cells is not well understood.
Purpose of the Study:
- To investigate the spatial relationship between Rho and RNAP in Salmonella.
- To determine the functional and localization consequences of N-terminal Rho modifications.
Main Methods:
- Constructed intragenic, in-frame fusions of Rho with fluorescent proteins (mCherry, sfGFP) in Salmonella.
- Assessed Rho function in vitro and bacterial growth rates.
- Utilized structured illumination microscopy (SIM) to visualize Rho and RNAP localization in single cells.
Main Results:
- mCherry fusion (RhoΔ48::mCherry) retained wild-type termination activity, unlike sfGFP fusion.
- Both Rho constructs localized differently from RNAP, with RNAP associating with the nucleoid and Rho distributed throughout the cell.
- Spatial partitioning persisted in stationary phase, with Rho accumulating at the cell periphery.
Conclusions:
- Rho and RNAP exhibit distinct spatial distributions within bacterial cells, challenging the notion of them being tightly coupled.
- The N-terminus of Rho, particularly the first 48 residues, influences its function and potentially its localization.
- The widespread cytoplasmic distribution of Rho suggests roles beyond transcription termination.
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