Inhibitor sensitivity of light-dependent oxygen reduction in chromatophores from wild-type and an oxidase-deficient mutant of Rhodopseudomonas capsulata

Raya Bittan*, Ayala Hochman, Ezra Yagil, Chanoch Carmeli

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Chromatophores from Rhodopseudomonas capsulata cells grown semiaerobically in the dark oxidize NADH, succinate, and dichlorophenolindophenol. In the presence of N3- these activities are inhibited, but light induces oxidation of dichlorophenolindophenol with O2 as a terminal electron acceptor. Cyanide also inhibits electron transport but much higher concentrations are required to inhibit the photooxidation than the dark oxidation. The photooxidation was studied in a mutant strain of Rhodopseudomonas capsulata (YIV) which cannot grow anaerobically in the light, but similarly to the wild type, grows in the presence of oxygen. Chromatophores from YIV mutant catalyze photophosphorylation and dark oxidation activities with the same properties as those of the wild type. However, the rate of photooxidation in the mutant is only one-third that of the wild type. Based on the differential inhibitor sensitivity and on the mutation it is suggested that the photooxidase is different from the two respiratory oxidases and that this photooxidation activity might be essential for growth of the cells under anaerobic conditions in the light.

Original languageEnglish
Pages (from-to)276-283
Number of pages8
JournalArchives of Biochemistry and Biophysics
Volume209
Issue number1
DOIs
StatePublished - Jun 1981

Funding

FundersFunder number
rael-USA Binational Foundation

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