Bacterial Na+ energetics.
Novel observations related to the Na+-linked energy transduction in bacterial membranes are considered. It is concluded that besides the well-known systems based on the circulation of protons, there are those based on the circulation of Na+. In some cases, H+ and Na+ cycles co-exist in one and the same membrane. Representatives of the 'sodium world', i.e. cells possessing primary Na+ pumps (delta mu Na generators and consumers) are found in many genera of bacteria. Among the delta mu Na generators, one should mention Na+-NADH-quinone reductase and Na+-terminal oxidase of the respiratory chain, Na+-decarboxylases and Na+-ATPases. For delta mu Na consumers, there are Na+-ATP-synthases, Na+-metabolite symporters and Na+ motors. Sometimes, one and the same enzyme can transport H+ or, alternatively, Na+. For instance, an Na+-ATP-synthase of the F0F1 type translocates H+ when Na+ is absent. Employment of the Na+ cycle, apart from or instead of the H+ cycle, increases the resistance of bacteria to alkaline or protonophore-containing media and, apparently, to some other unfavourable conditions.
Skulachev
V P
VP
Department of Bioenergetics, A.N. Belozersky Laboratory of Molecular Biology and Bioorganic Chemistry, Moscow State University, USSR.
D001419:Bacteria / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D010084:Oxidation-Reduction; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase