High-speed in-line force mapping unveils E. coli cell division dynamics

Light and electron microscopy have distinct limitations. Light microscopy makes it difficult to resolve smaller and smaller features, and electron microscopy resolves small structures, but samples must be meticulously prepared, killing any live specimens.

The researchers published their study in the January 29 issue of Science Advances.

During E. coli cell division, the researchers observed increased mechanical stiffening of the cell division site. The researchers hypothesize this stiffening could be due to localized membrane tension and local cell wall thickening. "The division site becomes much stiffer than the surrounding cell, hinting at large internal stresses that are needed to deform the membrane and separate the cells," said Ganser.

During division, the membrane also formed visible bridges between the two daughter cells that stretched and eventually broke. The creation and eventual breakage of these bridges lasted an average of 242 s ± 99 s (mean ± standard deviation) and was observed seven times. The entire division process is provided as a supplementary video in the online version of the research paper.

The team also observed a weak spot, less than 100 nm in diameter, in a dividing E. coli cell that ruptured, causing cell depressurization and death. Interestingly, the bursting cell caused depressurization of both left and right daughter cells, indicating that the cells were not completely separated internally. This observation suggests that HS-iFM may be useful in determining the timing of different steps during the division of E. coli and other bacteria.

The research team acknowledges the great potential of the HS-iFM technique for studying a wide variety of biological samples and organisms, including E. coli. "In the [future], we will use our technique to study the dynamic and localized effect of external stimuli, [such as] antibiotics, to the nanomechanical properties of membranes of living bacteria," said Ganser. The researchers also envision using HS-iFM to study the transient nanomechanical properties of polymers. Ideally, the team will increase the speed and resolution of the technique to visually capture the mechanical properties of molecules as small as individual proteins.

The co-authors of the research paper are Shigetaka Nishiguchi from the Exploratory Research Center on Life and Living Systems at the National Institutes of Natural Sciences in Okazaki, Japan; Feng-Yueh Chan from the Department of Physics at Nagoya University in Nagoya, Japan; and Takayuki Uchihashi from the Exploratory Research Center on Life and Living Systems at the National Institutes of Natural Sciences and the Department of Physics at Nagoya University.

This research was supported by JSPS KAKENHI Grant Number JP23H04874 in a Grant-in-Aid for Transformative Research Areas "Materials Science of Meso-Hierarchy" and 24K01309, 22K18943; by JST, CREST Grant Number JPMJCR21L2, Japan; and MEXT Promotion of Development of a Joint Usage/Research System Project: Coalition of Universities for Research Excellence Program (CURE) Grant Number JPMXP1323015482.

Source:

National Institutes of Natural Sciences

Journal reference: