大腸菌由来L型菌NC7における細胞容積の調節

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.