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

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...

Correction to: Direct observation of a crescent-shape chromosome in expanded Bacillus subtilis cells (Nature Communications, (2024), 15, 1, (2737), 10.1038/s41467-024-47094-x)

Correction to: Nature Communicationhttps://doi.org/10.1038/s41467-024-47094-x, published online 28 March 2024 The original version of this article contained an error in the “Acknowledgement “section. The original version read “We also acknowledge funding for the work in S.G. lab by the Swiss National Science Foundation (grant number: 310030L...

MukBEF-dependent chromosomal organization in widened Escherichia coli

The bacterial chromosome is spatially organized through protein-mediated compaction, supercoiling, and cell-boundary confinement. Structural Maintenance of Chromosomes (SMC) complexes are a major class of chromosome-organizing proteins present throughout all domains of life. Here, we study the role of the Escherichia coli SMC complex MukBEF...

Microwell-enhanced optical rapid antibiotic susceptibility testing of single bacteria

Bacteria that are resistant to antibiotics present an increasing burden on healthcare. To address this emerging crisis, novel rapid antibiotic susceptibility testing (AST) methods are eagerly needed. Here, we present an optical AST technique that can determine the bacterial viability within 1 h down to a resolution of single bacteria. The...

Probing nanomotion of single bacteria with graphene drums

Motion is a key characteristic of every form of life¹. Even at the microscale, it has been reported that colonies of bacteria can generate nanomotion on mechanical cantilevers², but the origin of these nanoscale vibrations has remained unresolved^3,4. Here, we present a new technique using drums made of...

CENP-B-mediated DNA loops regulate activity and stability of human centromeres

Chromosome inheritance depends on centromeres, epigenetically specified regions of chromosomes. While conventional human centromeres are known to be built of long tandem DNA repeats, much of their architecture remains unknown. Using single-molecule techniques such as AFM, nanopores, and optical tweezers, we find that human centromeric DNA...

Extracting and characterizing protein-free megabase-pair DNA for in vitro experiments

Chromosome structure and function is studied using various cell-based methods as well as with a range of in vitro single-molecule techniques on short DNA substrates. Here, we present a method to obtain megabase-pair-length deproteinated DNA for in vitro studies. We isolated chromosomes from bacterial cells and enzymatically digested the...

Mechanisms for Chromosome Segregation in Bacteria

The process of DNA segregation, the redistribution of newly replicated genomic material to daughter cells, is a crucial step in the life cycle of all living systems. Here, we review DNA segregation in bacteria which evolved a variety of mechanisms for partitioning newly replicated DNA. Bacterial species such as Caulobacter crescentus and...

DNA sequence-directed cooperation between nucleoid-associated proteins

Nucleoid-associated proteins (NAPs) are a class of highly abundant DNA-binding proteins in bacteria and archaea. While both the composition and relative abundance of the NAPs change during the bacterial growth cycle, surprisingly little is known about their crosstalk in mutually binding and stabilizing higher-order nucleoprotein complexes in...

Direct observation of independently moving replisomes in Escherichia coli

The replication and transfer of genomic material from a cell to its progeny are vital processes in all living systems. Here we visualize the process of chromosome replication in widened E. coli cells. Monitoring the replication of single chromosomes yields clear examples of replication bubbles that reveal that the two replisomes move...

Interplay between Confinement and Drag Forces Determine the Fate of Amyloid Fibrils

The fine interplay between the simultaneous stretching and confinement of amyloid fibrils is probed by combining a microcapillary setup with atomic force microscopy. Single-molecule statistics reveal how the stretching of fibrils changed from force to confinement dominated at different length scales. System order, however, is solely ruled by...

Direct imaging of the circular chromosome in a live bacterium

Although the physical properties of chromosomes, including their morphology, mechanics, and dynamics are crucial for their biological function, many basic questions remain unresolved. Here we directly image the circular chromosome in live E. coli with a broadened cell shape. We find that it exhibits a torus topology with, on average, a lower...