Evolutionary origins of mechanosensitive ion channels.
According to the recent revision, the universal phylogenetic tree is composed of three domains: Eukarya (eukaryotes), Bacteria (eubacteria) and Archaea (archaebacteria). Mechanosensitive (MS) ion channels have been documented in cells belonging to all three domains suggesting their very early appearance during evolution of life on Earth. The channels show great diversity in conductance, selectivity and voltage dependence, while sharing the property of being gated by mechanical stimuli exerted on cell membranes. In prokaryotes, MS channels were first documented in Bacteria followed by their discovery in Archaea. The finding of MS channels in archaeal cells helped to recognize and establish the evolutionary relationship between bacterial and archaeal MS channels and to show that this relationship extends to eukaryotic Fungi (Schizosaccharomyces pombe) and Plants (Arabidopsis thaliana). Similar to their bacterial and archaeal homologues, MS channels in eukaryotic cell-walled Fungi and Plants may serve in protecting the cellular plasma membrane from excessive dilation and rupture that may occur during osmotic stress. This review summarizes briefly some of the recent developments in the MS channel research field that may ultimately lead to elucidation of the biophysical and evolutionary principles underlying the mechanosensory transduction in living cells.
Martinac
Boris
B
Department of Pharmacology, QEII Medical Center, The University of Western Australia, WA 6009, Crawley, Australia. bmartinac@receptor.pharm.uwa.au
Kloda
Anna
A
D000595:Amino Acid Sequence; D001105:Archaea / Q000235:genetics / Q000502:physiology; D005075:Biological Evolution; D007473:Ion Channels / Q000502:physiology*; D008051:Lipid Bilayers; D040542:Mechanotransduction, Cellular; D008969:Molecular Sequence Data; D018408:Patch-Clamp Techniques; D010802:Phylogeny; D011312:Pressure; D017433:Protein Structure, Secondary
D007473:Ion Channels; D008051:Lipid Bilayers