The long-term goal of research in the Haswell lab is to reveal the molecular mechanisms that underlie the perception and transduction of mechanical signals in plants. Many organisms sense and respond to mechanical forces, and one way in which this can be accomplished is through the activation of mechanosensitive (MS) ion channels. Land plants provide a particularly relevant model system for the study of MS channels, as numerous MS channel activities have been identified in plant membranes, and they are implicated in a wide range of physiological processes. However, we do not know the molecular identity of the MS channels involved, nor how their activities might be regulated. To begin to gain insight into the plant mechanosensory apparatus, we have undertaken the characterization of ten Arabidopsis thaliana homologs of the bacterial mechanosensor MscS. We have discovered that plant MscS homologs are not simple safety valves, but are regulated channels with distinct and diverse roles at the organellar, cellular, and organismal level. Click here for coverage in the popular press and here for project outcomes aimed at a general audience.

*Mechanosensitive Channels & Plant Gravity Perception

In the gravity-sensing cells of the root tip, mechanosensitive channels have been proposed to mediate gravity perception from the envelope of sedimenting amyloplasts (1), and from the ER onto which amyloplasts sediment (2). In all cells, mechanosensitive channels could mediate gravity perception from the plasma membrane (3). We aim to investigate the role played by MSL and other mechanosensitive channels in the perception of and response to gravity.

*Structural, Functional, and Regulatory Diversity in the MscS Family

MscS homologs are widely dispersed among bacterial and plant lineages, are found in some fungi, but have not been identified in plants. Our investigations are beginning to reveal much how MscS-Like proteins have diverged with respect to structure, function and mechanisms of regulation.We have recently discovered that plant-specific domains confer plant-specific functions and modes of regulation to MscS-Like proteins in Arabidopsis thaliana.

*Electrophysiology of Plant and Bacterial MS Channels

We have used single channel patch-clamp electrophysiology to characterize E. coli MscS and Arabidopsis MSL8 and MSL10 expressed in Xenopus laevis oocytes. These studies establish that MSLs are bonafide mechanosensitive ion channels, and their behavior in oocytes closely resembles MSL-dependent activities in Arabidopsis root and pollen protoplasts. Differences in the behavior of MSL10, MSL8 and MscS may have implications for their respective roles in plant and bacterial physiology.

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Contact Info

Department of Biology, Box 1137
One Brookings Drive
Saint Louis, MO  63130
Lab: McDonnell 249  314.935.9634
Liz's Office: McDonnell 221  314.935.9223

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Meet us in person:

ICAR 2017, St. Louis, June
Plant Development, Vermont, August
Abiotic Stress, Asilomar, October
Plant Science Symposium, Zurich, November