大腸菌由来L型菌NC7における細胞容積の調節

Abstract

The ATPase inhibitor dicyclohexylcarbodiimide (DCCD), which collapse the chemical and electrical components of the proton motive force, caused rapid cell swelling. Addition of extracellular osmotic salt such as CaCl_2 prevented the swelling of DCCD-treated cells incubated in NaCl solution. Ionophore nigericin, which collapse the proton gradient by promoting electroneutral K+ / H+ exchange , and protonophore carbonylcyanide-m-chlorophenylhydrazone(CCCP, 10 μM) induced osmotic swelling in NaCl solution, but not in CaCl_2.External solutes such as CaCl_2 prevented the swelling of DCCD-treated cells incubated in NaCl. Ionophore valinomycin , collapse membrane potential in the presence of KCI, falled to induce swelling in NaCl solution. These results show that in L-form NC7 the swelling was induced by the collapse of the electrochemical gradient of proton. Therefore, it was postulated that Na+ that diffused into the cell was extruded by a Na+ / H+ antiport energized by the proton motive force to maintain constant cell volume.