Direct observation of a crescent-shape chromosome in expanded Bacillus subtilis cells

Direct observation of a crescent-shape chromosome in expanded Bacillus subtilis cells

Tišma, M. (TU Delft BN/Cees Dekker Lab)
Bock, Florian Patrick (University of Lausanne)
Kerssemakers, J.W.J. (TU Delft BN/Cees Dekker Lab)
Antar, Hammam (University of Lausanne)
Japaridze, A. (TU Delft Dynamics of Micro and Nano Systems)
Gruber, Stephan (University of Lausanne)
Dekker, C. (TU Delft BN/Cees Dekker Lab)

2024

Bacterial chromosomes are folded into tightly regulated three-dimensional structures to ensure proper transcription, replication, and segregation of the genetic information. Direct visualization of chromosomal shape within bacterial cells is hampered by cell-wall confinement and the optical diffraction limit. Here, we combine cell-shape manipulation strategies, high-resolution fluorescence microscopy techniques, and genetic engineering to visualize the shape of unconfined bacterial chromosome in real-time in live Bacillus subtilis cells that are expanded in volume. We show that the chromosomes predominantly exhibit crescent shapes with a non-uniform DNA density that is increased near the origin of replication (oriC). Additionally, we localized ParB and BsSMC proteins – the key drivers of chromosomal organization – along the contour of the crescent chromosome, showing the highest density near oriC. Opening of the BsSMC ring complex disrupted the crescent chromosome shape and instead yielded a torus shape. These findings help to understand the threedimensional organization of the chromosome and the main protein complexes that underlie its structure.

http://resolver.tudelft.nl/uuid:c86b11d0-5c68-4301-a916-d35a7e302444

https://doi.org/10.1038/s41467-024-47094-x

2041-1723

Nature Communications, 15 (1)

Institutional Repository

journal article

© 2024 M. Tišma, Florian Patrick Bock, J.W.J. Kerssemakers, Hammam Antar, A. Japaridze, Stephan Gruber, C. Dekker