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Oxygen dependence of photosynthetic electron transport in a bacteriochlorophyll‐containing rhizobium
Author(s) -
Kramer David M,
Kanazawa Atsuko,
Fleischman Darrell
Publication year - 1997
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(97)01300-8
Subject(s) - photosynthesis , anoxygenic photosynthesis , electron acceptor , rhizobium , photochemistry , electron transport chain , chemistry , bacteriochlorophyll , electron donor , oxygen , anaerobic exercise , phototroph , biology , biochemistry , catalysis , physiology , organic chemistry , gene
Bacteriochlorophyll‐containing rhizobia, which form nitrogen‐fixing nodules on the stems and roots of the legume Aeschynomene , grow photosynthetically only in the presence of oxygen or auxiliary electron acceptors. We show that, in whole cells of the Rhizobium strain BTAi 1, a single‐turnover excitation flash photooxidized c ‐type cytochrome under aerobic but not anaerobic conditions. Light‐induced fluorescence yield changes show that under anaerobic conditions, the primary acceptor quinone, Q A , is predominantly in the reduced state and so unable to accept electrons. Thus, as is the case for the aerobic photosynthetic bacterium Roseobacter denitrificans , over‐reduction of Q A likely prohibits photosynthesis under anaerobic conditions.