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The symbiotically essential cbb 3 ‐type oxidase of Bradyrhizobium japonicum is a proton pump
Author(s) -
Arslan Engin,
Kannt Aimo,
Thöny-Meyer Linda,
Hennecke Hauke
Publication year - 2000
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(00)01277-1
Subject(s) - valinomycin , chemistry , vesicle , bradyrhizobium japonicum , cytochrome c oxidase , electrochemical gradient , biochemistry , oxidase test , chemiosmosis , membrane potential , biophysics , membrane , biology , atp synthase , mitochondrion , enzyme , bacteria , rhizobiaceae , symbiosis , genetics
Purified cbb 3 ‐type oxidase of Bradyrhizobium japonicum was reconstituted into phospholipid vesicles. Tight vesicles were obtained as shown by the disturbance of ΔpH with CCCP and the membrane potential with valinomycin, which led to a six‐fold increase in cytochrome c oxidase activity. The vesicles were thus suitable for proton translocation experiments. In the presence of valinomycin, a pulse with reduced cytochrome c caused an acidification with a subsequent alkalinization, whereas the same pulse caused only an alkalinization in the presence of valinomycin plus CCCP. We conclude that the cbb 3 ‐type oxidase of B. japonicum is a proton pump.