Unbiased proteomic and forward genetic screens reveal that mechanosensitive ion channel MSL10 functions at ER-plasma membrane contact sites in Arabidopsis thaliana

Abstract

Mechanosensitive (MS) ion channels are an evolutionarily conserved way for cells to sense mechanical forces and transduce them into ionic signals. The channel properties of Arabidopsis thaliana MscS-Like (MSL)10 have been well studied, but how MSL10 signals remains largely unknown. To uncover signaling partners of MSL10, we employed both a proteomic screen and a forward genetic screen; both unexpectedly implicated ER-plasma membrane contact sites (EPCSs) in MSL10 function. The proteomic screen revealed that MSL10 associates with multiple proteins associated with EPCSs. Of these, only VAMP-associated proteins (VAP)27-1 and VAP27-3 interacted directly with MSL10. The forward genetic screen, for suppressors of a gain-of-function MSL10 allele (msl10-3G, MSL10S640L), identified mutations in the synaptotagmin (SYT)5 and SYT7 genes. We also found that EPCSs were expanded in leaves of msl10-3G plants compared to the wild type. Taken together, these results indicate that MSL10 can be found at EPCSs and functions there, providing a new cell-level framework for understanding MSL10 signaling. In addition, placing a mechanosensory protein at EPCS provides new insight into the function and regulation of this type of subcellular compartment.

Keep in contact: multiple roles of endoplasmic reticulum–membrane contact sites and the organelle interaction network in plants

“…As the EPCS occupies a large portion of the cell surface (larger than 10%), its regulation of ion channel activity is essential in neuronal physiology (Johnson et al ., 2018). Recent proteomic and forward genetic screens revealed that a PM‐localised mechanosensitive (MS) ion channel, MSL10, interacts with VAP27 in Arabidopsis (Codjoe et al ., 2022), suggesting a similar mechanism may exist in plants. It is highly possible that in certain cell types, for example guard cells, additional regulation of ion channels is important.…”

“…Recent proteomic and forward genetic screens revealed that a PMlocalised mechanosensitive (MS) ion channel, MSL10, interacts with VAP27 in Arabidopsis (Codjoe et al, 2022), suggesting a similar mechanism may exist in plants. It is highly possible that in certain cell types, for example guard cells, additional regulation of ion channels is important.…”

Root osmotic sensing from local perception to systemic responses

“…This response is dependent on the phosphorylation of MSL10 N-terminus (Veley et al 2014;. In a recent preprint, MSL10 was found to localize and function at ER-plasma membrane contact sites (EPCSs) (Codjoe et al 2022). In plants, EPCSs regulate lipid homeostasis between compartment and cell integrity (Schapire et al 2008;Ruiz-Lopez et al 2021).…”