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Lee J, Jha K, Harper CE, Zhang W, Ramsukh M, Bouklas N, Dörr T, Chen P, Hernandez CJ. Determining the Young's Modulus of the Bacterial Cell Envelope. ACS Biomater Sci Eng 2024; 10:2956-2966. [PMID: 38593061 DOI: 10.1021/acsbiomaterials.4c00105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
Bacteria experience substantial physical forces in their natural environment, including forces caused by osmotic pressure, growth in constrained spaces, and fluid shear. The cell envelope is the primary load-carrying structure of bacteria, but the mechanical properties of the cell envelope are poorly understood; reports of Young's modulus of the cell envelope of Escherichia coli range from 2 to 18 MPa. We developed a microfluidic system to apply mechanical loads to hundreds of bacteria at once and demonstrated the utility of the approach for evaluating whole-cell stiffness. Here, we extend this technique to determine Young's modulus of the cell envelope of E. coli and of the pathogens Vibrio cholerae and Staphylococcus aureus. An optimization-based inverse finite element analysis was used to determine the cell envelope Young's modulus from observed deformations. The Young's modulus values of the cell envelope were 2.06 ± 0.04 MPa for E. coli, 0.84 ± 0.02 MPa for E. coli treated with a chemical (A22) known to reduce cell stiffness, 0.12 ± 0.03 MPa for V. cholerae, and 1.52 ± 0.06 MPa for S. aureus (mean ± SD). The microfluidic approach allows examination of hundreds of cells at once and is readily applied to Gram-negative and Gram-positive organisms as well as rod-shaped and cocci cells, allowing further examination of the structural causes behind differences in cell envelope Young's modulus among bacterial species and strains.
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Affiliation(s)
- Junsung Lee
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Karan Jha
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Christine E Harper
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, New York 14853, United States
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Wenyao Zhang
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Malissa Ramsukh
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Nikolaos Bouklas
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Tobias Dörr
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York 14853, United States
- Department of Microbiology, Cornell University, Ithaca, New York 14853, United States
- Cornell Institute of Host-Microbe Interactions and Disease, Cornell University, Ithaca, New York 14853, United States
| | - Peng Chen
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Christopher J Hernandez
- Departments of Bioengineering and Therapeutic Sciences and Orthopaedic Surgery, UC San Francisco, California 94143, United States
- Chan Zuckerberg Biohub, San Francisco, California 94158, United States
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Johnson SC, Veres J, Malcolm HR. Exploring the diversity of mechanosensitive channels in bacterial genomes. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2021; 50:25-36. [PMID: 33244613 DOI: 10.1007/s00249-020-01478-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 10/08/2020] [Accepted: 11/08/2020] [Indexed: 10/22/2022]
Abstract
Mechanosensitive ion channels are responsible for touch sensation and proprioception in higher level organisms such as humans and recovery after osmotic stress in bacteria. Bacterial mechanosensitive channels are homologous to either the mechanosensitive channel of large conductance (MscL) or the mechanosensitive channel of small conductance (MscS). In the E. coli genome there are seven unique mechanosensitive channels, a single MscL homologue, and six MscS homologues. The six MscS homologues are members of the diverse MscS superfamily of ion channels, and these channels show variation on both the N and C termini when compared to E. coli MscS. In bacterial strains with phenotypic analysis of the endogenous mechanosensors, the quantity of MscS superfamily members in the genome range from 2 to 6 and all of the strains contain a copy of MscL. Here, we show an in-depth analysis of over 150 diverse bacterial genomes, encompassing nine phyla, to determine the number of genomes that contain an MscL homologue and the average number of MscS superfamily members per genome. We determined that the average genome contains 4 ± 3 MscS homologues and 67% of bacterial genomes encode for a MscL homologue.
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Affiliation(s)
- Sarah C Johnson
- Department of Chemistry, University of North Florida, Jacksonville, FL, USA
| | - Jordyn Veres
- Department of Chemistry, University of North Florida, Jacksonville, FL, USA
| | - Hannah R Malcolm
- Department of Chemistry, University of North Florida, Jacksonville, FL, USA.
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