Mechanosensitive ion channel MscL controls ionic fluxes during cold and heat stress in Synechocystis

Abstract

Calcium plays an essential role in a variety of stress responses of eukaryotic cells; however, its function in prokaryotes is obscure. Bacterial ion channels that transport Ca(2+) are barely known. We investigated temperature-induced changes in intracellular concentration of Ca(2+), Na(+) and K(+) in the cyanobacterium Synechocystis sp. strain PCC 6803 and its mutant that is defective in mechanosensitive ion channel MscL. Concentration of cations rapidly and transiently increased in wild-type cells in response to cold and heat treatments. These changes in ionic concentrations correlated with the changes in cytoplasmic volume that transiently decreased in response to temperature treatments. However, no increase in ionic concentrations was observed in the MscL-mutant cells. It implies that MscL functions as a non-specific ion channel, and it participates in regulation of cell volume under temperature-stress conditions.

Rapid Freezing Enables Aminoglycosides To Eradicate Bacterial Persisters via Enhancing Mechanosensitive Channel MscL-Mediated Antibiotic Uptake

“…Collectively, our observations, in conjunction with studies from Blount and coworkers on the MscL-mediated uptake of dihydrostreptomycin under conventional treatment conditions (62,63), strongly suggest that MscL directly mediates aminoglycoside uptake under freezing conditions. MscL, a mechanosensitive ion channel, is well known to be activated in response to changes in membrane tension as elicited by osmotic shock, cold/heat shock stresses, and/or other types of mechanical forces (73)(74)(75). Conceivably, freezing leads to membrane damage and destabilization ( Fig.…”

Glycogen deficiency enhances carbon partitioning into glutamate for an alternative extracellular metabolic sink in cyanobacteria

“…Homology search revealed that PCC 7942 harbors three putative MSC genes; the large conductance mechanosensitive channel protein gene mscL (Synpcc7942_1991) homologous to E. coli mscL gene, the mechanosensitive ion channel family protein gene (Synpcc7942_0610) homologous to E. coli ybiO gene, and the mechanosensitive ion channel gene (Synpcc7942_0664) homologous to E. coli mscM, mscS , and mscK genes. Although the role of MSCs in cyanobacteria has not been thoroughly examined, the mscL gene in PCC 6803 has been found to contribute to hypoosmotic stress adaptation and Ca 2+ transport 26 , 27 . In the present study, the increased extracellular levels and decreased intracellular levels of Lac in the Δ glgC mutant also supported the hypothesis that MSCs are activated by glycogen deficiency (Figs.…”

Genetic, Genomics, and Responses to Stresses in Cyanobacteria: Biotechnological Implications

“…New rapidly growing unicellular cyanobacteria have been recently described, namely, the freshwater strains Synechococcus UTEX 2973 [149], Synechococcus PCC 11801 [150], and Synechococcus PCC 11802 [151] and the marine strain Synechococcus PCC 11901 [80,152]. Synechococcus PCC 11901 tolerates high temperatures, up to 43 • C, which are non-optimal for Synechococcus UTEX 2973 [150,153], Synechococcus PCC 11801 [150,151], and Synechococcus PCC 7942 [154], and even detrimental to Synechocystis PCC 6803 [29,155]. Synechococcus PCC 11801 [150], Synechococcus PCC 11802 [151], and Synechococcus PCC 11901 [152] are naturally transformable, unlike Synechococcus UTEX2973 [150].…”