Novel Na+-Dependent Respiration in Hyperthermophilic Archaeon, Thermococcus onnurineus NA1

Abstract

Chemiosmotic energy transduction to ATP synthesis is the most basic process in life form. Throughout the prokaryotic membranes or mitochondrial inner membranes, energy-transducing protein complexes help transform the chemical energy from the cells metabolic intake into various useful forms of energy for the cell. Some of these complexes couple reduction-oxidation (redox) reactions to transporting and establishing chemiosmotic gradient across the membrane to drive otherwise energetically unfavorable process such as ATP synthesis and assorted transporters of other ions and/or molecules. Complex I is the most well known energy transducing enzyme that consists of 14 enzymes in bacteria, transferring electrons from NADH through a complex chain to quinones which process pumps protons across membrane and then generate proton coupled electrical membrane potential. Complex I is an example of the modular structure composed of electron donor/transfer module, connecting module, and intrinsic membrane module in Escherichia coli, has been also thought to have close relationship with Group 4 hydrogenases. The group 4 hydrogenases that widely distributed among bacteria and archaea, have been recognized as a energy converting enzyme composed in modular structure as well as the key enzyme in hydrogen production. Of particular, Mbh hydrogenase from Pyrococcus furiosus which catalyzes the reduction of H+ with electrons derived from ree cells metabolic intake into various useful forms of energy for the cell. Some of these complexes couple reduction-oxidation (redox) reactions to transporting and establishing chemiosmotic gradient across the membrane to drive otherwise energetically unfavorable process such as ATP synthesis and assorted transporters of other ions and/or molecules. Complex I is the most well known energy transducing enzyme that consists of 14 enzymes in bacteria, transferring electrons from NADH through a complex chain to quinones which process pumps protons across membrane and then generate proton coupled electrical membrane potential. Complex I is an example of the modular structure composed of electron donor/transfer module, connecting module, and intrinsic membrane module in Escherichia coli, has been also thought to have close relationship with Group 4 hydrogenases. The group 4 hydrogenases that widely distributed among bacteria and archaea, have been recognized as a energy converting enzyme composed in modular structure as well as the key enzyme in hydrogen production. Of particular, Mbh hydrogenase from Pyrococcus furiosus which catalyzes the reduction of H+ with electrons derived from re