Open AccessDemonstration of a K + /H + exchange activity in a photodenitrifier, Rhodopseudomonas sphaeroides forma sp. denitrificans
Author(s) -
Kundu Balaram,
Nicholas D.J.D.
Publication year - 1986
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1986.tb01413.x
Subject(s) - antiporter , intracellular ph , nigericin , intracellular , rhodobacter sphaeroides , chemistry , electrochemical gradient , suspension (topology) , cyanide , biophysics , protonophore , membrane potential , ion transporter , rhodopseudomonas , nuclear chemistry , membrane , biochemistry , biology , photosynthesis , inorganic chemistry , mathematics , homotopy , pure mathematics
Washed cells of Rhodopseudomonas sphaeroides forma sp. denitrificans , grown under photodenitrifying conditions, exhibited K + uptake dependent on the transmembrane proton gradient (Δ pH). These cells also acidified the suspension medium in response to K + pulses both aerobically and anaerobically in light and in the dark. The results indicate that the photodenitrifier has a reversible K + /H + exchange activity which reflects its role in regulating the intracellular K + concentration, as well as intracellular pH. The acidification of the external medium resulting from K + pulses was inhibited by carbonyl cyanide‐ m ‐chlorophenylhydrazone (CCCP) indicating that the antiporter is energy‐dependent. Addition of KCl to washed cells depolarized the membrane potential (Δψ) with a concomitant increase in ΔpH, indicating that the K + /H + antiporter was electrogenic.