The MscS Cytoplasmic Domain and Its Conformational Changes on the Channel Gating

The cytoplasmic cage domain of the mechanosensitive channel MscS is a sensor of macromolecular crowding

“…In the present work we show that MscS, the primary turgor-regulating valve in E. coli, is also one of the sensors of internal crowding. Following the earlier observations by Grajkowski et al (2005) and Koprowski et al (2007Koprowski et al ( , 2011, we have characterized MscS as the first sensor of cytoplasmic crowding and explained its adaptive inactivation mechanism in the context of a small cell encased in an elastic peptidoglycan sacculus. Although not all MscS homologues found in other species inactivate (Nakayama et al, 2013;Petrov et al, 2013), this mechanism has implications for the entire family of MscS-like channels carrying similar cytoplasmic cages that are structurally connected to the gate through the pore-lining helices.…”

“…1 ), from where the channel would be able to open by membrane tension transmitted through the peripheral helices to its gate ( Belyy et al, 2010a ). The previous searches for the gating-competent resting state and models for opening and inactivation considered primarily conformational changes in the transmembrane (TM) domain, although there were indications that the movements of the TM domain generates coupled movements in the “cage” ( Koprowski et al, 2007 ; Nomura et al, 2008 ; Machiyama et al, 2009 ).…”

“…Free-living microorganisms are frequently subjected to hydration stresses and possess robust osmoregulatory systems. In hyperosmotic conditions, bacteria accumulate ions and compatible organic osmolytes to retain water (Csonka and Hanson, 1991;Wood et al, 2001; The cytoplasmic cage domain of the mechanosensitive channel MscS is a sensor of macromolecular crowding models for opening and inactivation considered primarily conformational changes in the transmembrane (TM) domain, although there were indications that the movements of the TM domain generates coupled movements in the "cage" (Koprowski et al, 2007;Nomura et al, 2008;Machiyama et al, 2009).…”