The evolutionary 'tinkering' of MscS-like channels: generation of structural and functional diversity

The mechanosensitive channel of small conductance (MscS)-like channel superfamily is present in cell-walled organisms throughout all domains of life (Bacteria, Archaea and Eukarya). In bacteria, members of this channel family play an integral role in the protection of cells against acute downward shifts in environmental osmolarity. In this review, we discuss how evolutionary 'tinkering' has taken MscS-like channels from their currently accepted physiological function in bacterial osmoregulation to potential roles in processes as diverse as amino acid efflux, Ca(2+) regulation and cell division. We also illustrate how this structurally and functionally diverse family of channels represents an essential industrial component in the production of monosodium glutamate, an attractive antibiotic target and a rich source of membrane proteins for the studies of molecular evolution.