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

• Published in: Biophysical journal 2014-12, Vol.107 (11), p.2538-2545
• Main Authors: Bailey, Richard G., Turner, Robert D., Mullin, Nic, Clarke, Nigel, Foster, Simon J., Hobbs, Jamie K.
• Format: Article
• Language: English
• Subjects: Biomechanical Phenomena; Biophysics; Cell Biophysics; Cell cycle; Cell Cycle - drug effects; Cell Membrane - drug effects; Cell Wall - drug effects; Cell Wall - physiology; Cellular biology; Compressive Strength - drug effects; Membranes; Microbial Viability - drug effects; Microscopy; Microscopy, Atomic Force; Models, Biological; Staphylococcus aureus; Staphylococcus aureus - cytology; Staphylococcus aureus - drug effects; Staphylococcus aureus - physiology; Staphylococcus infections; Stress response; Surface Properties
• ISSN: 0006-3495; 1542-0086
• DOI: 10.1016/j.bpj.2014.10.036

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.