The differential action of metronidazole on nitrogen fixation, hydrogen metabolism, photosynthesis and respiration in Anabaena and Scenedesmus

Tetley, Richard M.; Bishop, Norman I.

doi:10.1016/0005-2728(79)90168-3

Cited by 54 publications

(25 citation statements)

References 26 publications

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“…Nitrogenase, however, can be selectively inactivated by exposing filaments to 100% 02 as suggested by Tetley and Bishop (29). We found that a 15-min exposure to 100%02 eliminated 95% of the C2H2-reducing activity, but only 20o of the oxyhydrogen reaction.…”

Section: Resultssupporting

confidence: 59%

“…Hydrogen uptake in the dark depends on the presence of 02 as an electron acceptor, however, light-driven H2 uptake also has been reported for Anabaena (3,29). If N2-fixing filaments were incubated under 100%o H2 in the presence of the PSII inhibitor DCMU, H2 was evolved upon illumination ( Fig.…”

Section: Resultsmentioning

confidence: 63%

“…In heterocystous blue- ' Supported by the College of Agricultural and Life Sciences, University of Wisconsin-Madison, by National Science Foundation grant green algae, uptake hydrogenase is confined to heterocysts (22) where it can couple to O2 uptake and provide a source of ATP (21). Light-dependent H2 uptake also has been reported (28,29), and H2 can provide electrons for C2H2 reduction in the light (3). This report more closely examines the light and dark reactions of uptake hydrogenase in whole filaments, isolated heterocysts, and hydrogenase-containing particles.…”

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confidence: 99%

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Light and Dark Reactions of the Uptake Hydrogenase in Anabaena 7120

Houchins¹,

Burris²

1981

Plant Physiol.

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Reactions of the uptake hydrogenase from Anabaena 7120 (A.T.C.C. 27893, Nostoc muscorum) were examined in whole filaments, isolated heterocysts, and membrane particles. Whole ifiaments or isolated heterocysts that contained nitrogenase consumed H2 in the presence of C2H2 or N2 in a light-dependent reaction. If nitrogenase was inactivated by O2 shock, filaments catalyzed H2 uptake to an unidentified endogenous acceptor in the light. Addition of N03-or N02-enhanced these rates. Isolated heterocysts consumed H2 in the dark in the presence of electron acceptors with positive midpoint potentials, and these reactions were not enhanced by light. With acceptors of negative midpoint potential, significant light enhancement of H2 uptake occurred. Maximum rates of light-dependent uptake were approximately 25% of the maximum dark rates observed. Membrane particles prepared from isolated heterocysts showed similar specificity for electron acceptors. These particles catalyzed a cyanidesensitive oxyhydrogen reaction that was inactivated by 02 at 02 concentrations above 2%. Light-dependent H2 uptake to low potential acceptors by these particles was inhibited by dibromothymoquinone but was insensitive to cyanide. In the presence of 02, light-dependent H2 uptake occurred sunultaneously with the oxyhydrogen reaction. The pH optima for both types of H2 uptake were near 7.0. These results further clarify the role of uptake hydrogenase in donating electrons to both the photosynthetic and respiratory electron transport chains of Anabaena.Uptake hydrogenases have been found in several aerobic N2-fixing organisms (1,6,12), and these enzymes share several common properties. They are membrane-bound (7,12,28), couple to 02 consumption via a Cyt-containing electron transport system, and through this reaction provide a source of ATP (7, 9, 21). Several authors have suggested that these uptake hydrogenases function to recycle the H2 evolved by nitrogenase (4,7,9,21).In blue-green algae, membrane-bound hydrogenases can couple to two different electron transport pathways. Peschek has demonstrated respiratory H2 uptake and photosynthetic H2 uptake in Anacystis nidulans (19,20) in which the hydrogenase was induced by growth under a gas phase containing H2. In the dark, both H2 uptake systems could react only with acceptors having a positive midpoint potential; however, upon illumination acceptors with a negative potential could also be reduced.

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Section: Resultssupporting

confidence: 59%

Section: Resultsmentioning

confidence: 63%

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confidence: 99%

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Light and Dark Reactions of the Uptake Hydrogenase in Anabaena 7120

Houchins¹,

Burris²

1981

Plant Physiol.

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“…Metronidazole concentrations of 20 V1M were required for 50% inhibition of growth when nitrogenase was derepressed, as compared to 800 FM for 50% inhibition in repressing conditions. This differential sensitivity was similar to results obtained in other studies and has been attributed to the reduction of metronidazole by low-potential redox reactions associated with nitrogenase activity, with the consequent generation of a toxic product(s) (21).…”

supporting

confidence: 89%

Spontaneous nif- Mutants of Rhodopseudomonas Capsulata

Wall

Love

Quinn³

1984

Advances in Nitrogen Fixation Research

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“…This enzyme is membrane-bound in all aerobic N,-fixing organisms and is unidirectional, catalysing only H, uptake in the intact cells. Recent evidence (Bothe et Peschek, 1979aPeschek, , b, 1980Tetley & Bishop, 1979) suggests that H, utilization proceeds by two different pathways in cyanobacteria. In the main pathway, the gas is consumed in an 0,-dependent reaction, being coupled to electron flow and to ATP formation of respiration.…”

Section: Introductionmentioning

confidence: 99%

The Number of Hydrogenases in Cyanobacteria

1981

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Cyanobacteria consume H, by two different pathways: the oxyhydrogen reaction and anaerobic, light-dependent H, utilization. The two pathways are shown here to be induced differently by incubating cyanobacteria anaerobically under H,. In the unicellular A nacystis nidulans and in N,-and NHi-grown Anabaena cylindrica and Nostoc muscorum, such treatment greatly enhances the activity of the oxyhydrogen reaction in all cell types. In contrast, the light-dependent pathway, determined by the H,-dependent photoreduction of NADP+, is demonstrable with higher activity only in heterocysts.Whereas the activity of the oxyhydrogen reaction is directly correlated to the structural integrity of membranes, there is an inverse correlation between membrane integrity and H, formation catalysed by hydrogenase. These findings, together with physiological considerations, suggest that a 'reversible' soluble hydrogenase does not exist in photoautotrophic cyanobacteria. No definite conclusions about the existence of two membrane-bound uptake hydrogenases are possible at present.

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The differential action of metronidazole on nitrogen fixation, hydrogen metabolism, photosynthesis and respiration in Anabaena and Scenedesmus

Cited by 54 publications

References 26 publications

Light and Dark Reactions of the Uptake Hydrogenase in Anabaena 7120

Light and Dark Reactions of the Uptake Hydrogenase in Anabaena 7120

Spontaneous nif- Mutants of Rhodopseudomonas Capsulata

The Number of Hydrogenases in Cyanobacteria

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