The dynamic hypoosmotic response of Vibrio cholerae relies on the mechanosensitive channel MscS

This is the authors' abstract. We don't add key points for this paper.

Highlights•Transmitted through freshwater, Vibrio cholerae experiences strong osmotic downshifts•Tension-activated channels VcMscS and VcMscL help to avoid swelling-induced lysis•VcMscS alone fulfills the osmotic rescuing function, whereas VcMscL alone does not•Osmolyte release kinetics and modeling predict the range of tolerable shock magnitudesSummaryVibrio cholerae adapts to osmotic down-shifts by releasing metabolites through two mechanosensitive (MS) channels, low-threshold MscS and high-threshold MscL. To investigate each channel's contribution to the osmotic response, we generated ΔmscS, ΔmscL, and double ΔmscL ΔmscS mutants in V. cholerae O395. We characterized their tension-dependent activation in patch-clamp, and the millisecond-scale osmolyte release kinetics using a stopped-flow light scattering technique. We additionally generated numerical models describing osmolyte and water fluxes. We illustrate the sequence of events and define the parameters that characterize discrete phases of the osmotic response. Survival is correlated to the extent of cell swelling, the rate of osmolyte release, and the completeness of post-shock membrane resealing. Not only do the two channels interact functionally, but there is also an up-regulation of MscS in the ΔmscL strain, suggesting transcriptional crosstalk. The data reveal the role of MscS in the termination of the osmotic permeability response in V. cholerae.