Mechanosensation is a ubiquitous phenomenon and a critical aspect of cell growth, morphology and development, yet it is poorly understood at the molecular and cellular levels. Experiments proposed here aim to reveal in molecular detail how cells and organelles employ mechanosensitive (MS) channels to respond to sudden changes in the surrounding environment, resulting in changes in osmotic pressure. Under these circumstances, water can rush into the cell resulting in a membrane tension that, if unchecked, can result in cell death. The goal of this research is to understand how membrane-bound mechanosensors are activated by environmental cues such as osmotic shock and how tension-sensitive channels mediate a protective physiological response. Bacterial MS channels of large (MscL) and small (MscS) conductance serve as a paradigm for the structural and biophysical analysis of mechanoresponsive proteins and for the physiological functions of MS channels across all domains of life. To develop an understanding of how they function, a number of different experiments have been designed. One key objective is to understand the function of MS channels at the cellular level by watching individual cells subjected to different rates and amplitudes of osmotic downshock. A newly developed microfluidics system will be used to impose rapid changes in osmotic environment on individual cells and organelles and to quantitatively measure the relationship between the number and type of MS channels and osmotic downshock survival. These physiological studies will be complemented by structural studies aimed at providing a richer understanding of MS channel conformations, how various elements of channel structure contribute to function and to quantitatively model the response of cells to downshock. The work performed on model bacterial and plant systems will form the foundation for investigation into the structure and function of MS channels in the life cycle and virulence of bacterial and protozoan human pathogens, and are therefore directly relevant to human health.

Public Health Relevance

Force-sensing is a critical aspect of cell growth, morphology and development. We will study in molecular detail how two families of stretch-activated membrane channels contribute to osmotic stress survival in model eukaryotic and prokaryotic systems and to virulence in selected human pathogens.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM084211-06
Application #
8728920
Study Section
Biochemistry and Biophysics of Membranes Study Section (BBM)
Program Officer
Chin, Jean
Project Start
2008-09-15
Project End
2017-08-31
Budget Start
2014-09-01
Budget End
2015-08-31
Support Year
6
Fiscal Year
2014
Total Cost
$437,539
Indirect Cost
$107,539
Name
California Institute of Technology
Department
Type
Schools of Engineering
DUNS #
009584210
City
Pasadena
State
CA
Country
United States
Zip Code
91125
Maksaev, Grigory; Shoots, Jennette M; Ohri, Simran et al. (2018) Nonpolar residues in the presumptive pore-lining helix of mechanosensitive channel MSL10 influence channel behavior and establish a nonconducting function. Plant Direct 2:
Herrera, Nadia; Maksaev, Grigory; Haswell, Elizabeth S et al. (2018) Elucidating a role for the cytoplasmic domain in the Mycobacterium tuberculosis mechanosensitive channel of large conductance. Sci Rep 8:14566
Chure, Griffin; Lee, Heun Jin; Rasmussen, Akiko et al. (2018) Connecting the dots between mechanosensitive channel abundance, osmotic shock, and survival at single-cell resolution. J Bacteriol :
Jensen, Gregory S; Fal, Kateryna; Hamant, Olivier et al. (2017) The RNA Polymerase-Associated Factor 1 Complex Is Required for Plant Touch Responses. J Exp Bot 68:499-511
Basu, Debarati; Haswell, Elizabeth S (2017) Plant mechanosensitive ion channels: an ocean of possibilities. Curr Opin Plant Biol 40:43-48
Einav, Tal; Phillips, Rob (2017) Monod-Wyman-Changeux Analysis of Ligand-Gated Ion Channel Mutants. J Phys Chem B 121:3813-3824
Hamant, Olivier; Haswell, Elizabeth S (2017) Life behind the wall: sensing mechanical cues in plants. BMC Biol 15:59
Lee, Chun Pong; Maksaev, Grigory; Jensen, Gregory S et al. (2016) MSL1 is a mechanosensitive ion channel that dissipates mitochondrial membrane potential and maintains redox homeostasis in mitochondria during abiotic stress. Plant J 88:809-825
Walton, Troy A; Idigo, Chinenye A; Herrera, Nadia et al. (2015) MscL: channeling membrane tension. Pflugers Arch 467:15-25
Hamilton, Eric S; Schlegel, Angela M; Haswell, Elizabeth S (2015) United in diversity: mechanosensitive ion channels in plants. Annu Rev Plant Biol 66:113-37

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