The Interplay between Cell Wall Mechanical Properties and the Cell Cycle in Staphylococcus aureus

Abstract

The nanoscale mechanical properties of live Staphylococcus aureus cells during different phases of growth were studied by atomic force microscopy. Indentation to different depths provided access to both local cell wall mechanical properties and whole-cell properties, including a component related to cell turgor pressure. Local cell wall properties were found to change in a characteristic manner throughout the division cycle. Splitting of the cell into two daughter cells followed a local softening of the cell wall along the division circumference, with the cell wall on either side of the division circumference becoming stiffer. Once exposed, the newly formed septum was found to be stiffer than the surrounding, older cell wall. Deeper indentations, which were affected by cell turgor pressure, did not show a change in stiffness throughout the division cycle, implying that enzymatic cell wall remodeling and local variations in wall properties are responsible for the evolution of cell shape through division.

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“…( fig. 6a), in good agreement to within experimental error with estimates (67,68), though as noted from super-resolution studies there can be significant variation of cell length depending on the specific stage in the cell cycle (24). The majority of our data have a major axis which is 30-50% longer than the minor access, indicating a mean cell aspect ratio of 1.4 ± 0.3 (fig.…”

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“…It is not chemistry alone that requires adaption of flexibility, but also the large and rigid substrate which needs to be torn. Bailey et al have shown that the newly formed peptidoglycan at the septum is stiffer and proposed that the subsequent drop in rigidity during division process is likely due to the peptidoglycan hydrolase activity 48 . This coincides with AtlA localization at the septal region and its proposed role in cell division 14,21 and their ability to cleave highly cross linked S. aureus peptidoglycan 19 .…”

Photoinduced chitosan–PEG hydrogels with long-term antibacterial properties

“…However, according to our antibacterial results, bactericidal effect is more pronounced on E. coli strains than on S. aureus ones. This can be explained by the thickness of the peptidoglycan layer between bacteria 68,69 . Indeed, E. coli, Gram negative, is protected by an outer membrane of liposaccharides, surrounding by a relatively thin layer of peptidoglycans (7-8 nm).…”