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Degli Esposti M, Martinez Romero E. A survey of the energy metabolism of nodulating symbionts reveals a new form of respiratory complex I. FEMS Microbiol Ecol 2016; 92:fiw084. [DOI: 10.1093/femsec/fiw084] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/18/2016] [Indexed: 01/18/2023] Open
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2
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Kuvaeva TM, Katashkina JI, Kivero AD, Smirnov SV. Novel NADPH-dependent L-aspartate dehydrogenases from the mesophilic nitrogen-fixing bacteria Rhodopseudomonas palustris and Bradyrhizobium japonicum. APPL BIOCHEM MICRO+ 2013. [DOI: 10.1134/s0003683813010109] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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3
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4
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Bacteroids from soybean root nodules: respiration and N
2
-fixation in flow-chamber reactions with oxyleghaemoglobin. ACTA ACUST UNITED AC 1997. [DOI: 10.1098/rspb.1990.0001] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Suspensions of bacteroids prepared from root nodules of glasshouse-grown soybeans were studied in a stirred chamber supplied with variable flows of solutions containing dissolved air, oxyleghaemoglobin and various energy sources. In experiments of up to 6 h duration, several steady states were established in which frequent measurements were made of the concentration of free, dissolved O
2
in the range 5–200 nM and of rates of O
2
consumption, CO
2
efflux and N
2
fixation. The principal findings were: (i) bacteroids were capable of efficient N
2
fixation without the supply of exogenous energy sources when respiring at 10–50 nM free O
2
. This endogenous respiration was enhanced after periods of supply of succinate or malate. (ii) Exogenous energy sources were of three types, those that were poorly utilized (glucose), those that enhanced endogenous respiration and supported efficient N
2
fixation (glutamate, 2-oxoglutarate) and succinate and malate, which promoted respiration but supported N
2
fixation inefficiently or in some circumstances inhibited it. It is proposed that succinate and malate act primarily to increase endogenous reserves that become the principal source of reducing power for N
2
fixation, (iii) Bacteroids have a terminal oxidase system with very high apparent affinity for O
2
(
s
0.5
≈ 5–8 nM) and complex kinetics (plots of
v
against
s
are sigmoidal;
n
app
> 1.8). This system was active with endogenous substrates and when glutamate or 2-oxoglutarate were supplied. With succinate or malate, respiration appeared to be the sum of endogenous activity plus O
2
consumption by a system with lower affinity for O
2
(
K
s
= 38 nM) and simple kinetics (
n
app
≈ 1). (iv) During the first hour of reactions there were changes in O
2
demand and oscillations in O
2
demand and CO
2
efflux followed supply or withdrawal of exogenous substrates. It is proposed that these changes are examples of phenotypic plasticity in these symbiotic bacteria.
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5
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O'Brian MR, Maier RJ. Molecular aspects of the energetics of nitrogen fixation in Rhizobium-legume symbioses. BIOCHIMICA ET BIOPHYSICA ACTA 1989; 974:229-46. [PMID: 2659085 DOI: 10.1016/s0005-2728(89)80239-7] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- M R O'Brian
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218
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6
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Lankhorst RM, Katinakis P, van Kammen A, van den Bos RC. Identification and Characterization of a Bacteroid-Specific Dehydrogenase Complex in
Rhizobium leguminosarum
PRE. Appl Environ Microbiol 1988; 54:3008-13. [PMID: 16347793 PMCID: PMC204419 DOI: 10.1128/aem.54.12.3008-3013.1988] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In membranes of
Rhizobium leguminosarum
bacteroids isolated from nitrogen-fixing pea root nodules, two different protein complexes with NADH dehydrogenase activity were detected. One of these complexes, with a molecular mass of 110 kilodaltons, was also found in membranes of free-living rhizobia, but the other, with a molecular mass of 550 kilodaltons, appeared to be present only in bacteroids. The bacteroid-specific complex, referred to as DH1, probably consists of at least four different subunits. Using antibodies raised against the separate polypeptides, we found that a 35,000-molecular-weight polypeptide (35K polypeptide) in the DH1 complex is bacteroid specific, while the other proposed subunits were also detectable in cytoplasmic membranes of free-living bacteria. Dehydrogenase complex DH1 is also present in bacteroids of a
R. leguminosarum nifA
mutant, indicating that the synthesis of the dehydrogenase is not dependent on the gene product of this
nif
-regulatory gene. A possible involvement of the bacteroid-specific DH1 complex in electron transport to nitrogenase is discussed.
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Affiliation(s)
- R M Lankhorst
- Department of Molecular Biology, Agricultural University, DreijenLaan 3, 6703 HA Wageningen, The Netherlands
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7
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Miller RW, McRae DG, Al-Jobore A, Berndt WB. Respiration supported nitrogenase activity of isolated Rhizobium meliloti bacteroids. J Cell Biochem 1988; 38:35-49. [PMID: 3220879 DOI: 10.1002/jcb.240380105] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Bacteroids having a high level of respiration-supported nitrogenase activity were isolated from nitrogen-fixing alfalfa root nodules. Gentle maceration under anaerobic conditions in the presence of sodium succinate and a fatty acid scavenging agent were employed in this method. A large proportion of isolated bacteroids retained a triple membrane structure as shown by transmission electron microscopy. Dicarboxylic acids of the TCA cycle (malate, fumarate, succinate), but not glutamate or aspartate, supported sufficient respiratory activity to supply the nitrogenase system with ATP and reducing equivalents and to protect the nitrogenase system from inactivation by 4% oxygen over a period of 20-30 min. Sugars did not support nitrogenase activity in intact bacteroids. The properties of the isolated bacteroids were ascribed to minimal damage to the cytoplasmic membrane and peribacteroidal membrane during isolation. With succinate as substrate and oxygen as terminal electron acceptor, initial nitrogenase activity was determined at 4% oxygen in the gas phase of the assay system employed. At this oxygen concentration, the sustained rate of acetylene reduction by respiring bacteroids was linear up to 30 min. Bacteroid activity declined rapidly with time of exposure to oxygen above 4% in the gas phase. The optimum temperature range for this activity was 10-20 degrees C. Nitrogenase activity was measurable at incubation temperatures below 10 degrees C under 4% oxygen. Functionally intact bacteroids had little nitrogenase activity under anaerobic conditions in the presence of an external source of ATP and reductant. Treatment of the bacteroids with chlorpromazine eliminated respiration-supported activity and rendered the bacteroid cell membrane permeable to external ATP. Bacteroids treated with chlorpromazine had high acetylene reducing activity with external ATP and dithionite in the absence of oxygen.
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Affiliation(s)
- R W Miller
- Plant Research Centre, Agriculture Canada, Ottawa, Ontario
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8
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Padan E, Schuldiner S. Intracellular pH and membrane potential as regulators in the prokaryotic cell. J Membr Biol 1987; 95:189-98. [PMID: 3295250 DOI: 10.1007/bf01869481] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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9
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Suzuki F, Zahler WL, Emerich DW. Acetoacetyl-CoA thiolase of Bradyrhizobium japonicum bacteroids: purification and properties. Arch Biochem Biophys 1987; 254:272-81. [PMID: 2883931 DOI: 10.1016/0003-9861(87)90103-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Acetoacetyl-CoA thiolase of Bradyrhizobium japonicum bacteroids has been purified greater than 130-fold. The enzyme has a molecular weight of 180,000 +/- 15,000 and consists of four identical subunits of 44,000 +/- 2,000. The enzyme was specific for acetoacetyl-CoA; ketodecanoyl-CoA did not serve as a substrate. Catalysis proceeds via a ping-pong mechanism. Iodoacetamide effectively inhibited the enzyme but acetoacetyl-CoA provided considerable protection against this compound. Magnesium was found to inhibit both the thiolysis reaction and the condensation reaction. Acetoacetyl-CoA thiolysis activity was not affected by potassium, ammonium, or several organic acids but was found to be inhibited by NADH. The inhibition by NADH may have an effect during the decline of the symbiosis.
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10
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11
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12
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Mason C, Hamer G, Bryers J. The death and lysis of microorganisms in environmental processes. FEMS Microbiol Lett 1986. [DOI: 10.1111/j.1574-6968.1986.tb01867.x] [Citation(s) in RCA: 112] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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13
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Bhandari B, Nicholas DJ. Proton motive force in washed cells of Rhizobium japonicum and bacteroids from Glycine max. J Bacteriol 1985; 164:1383-5. [PMID: 2999086 PMCID: PMC219346 DOI: 10.1128/jb.164.3.1383-1385.1985] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The components of the proton motive force (delta p), namely the membrane potential and the transmembrane pH gradient, were measured in washed cells of Rhizobium japonicum CC705 grown in cultures (5% O2-95% N2) in the presence of 10 mM KNO3 and in bacteroids from Glycine max. The delta p and its components remained reasonably constant in cells as well as in bacteroids at various stages of growth. The effects of uncouplers and ATPase inhibitors on the delta p and its components were determined in both cultured cells and bacteroids. The data indicated that a respiration-driven H+ translocation is the source of the delta p in both cultured cells and bacteroids.
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14
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Gober JW, Kashket ER. Measurement of the proton motive force in Rhizobium meliloti with the Escherichia coli lacY gene product. J Bacteriol 1985; 164:929-31. [PMID: 2997139 PMCID: PMC214343 DOI: 10.1128/jb.164.2.929-931.1985] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
An Escherichia coli lac operon constitutive for lacY was subcloned into the EcoRI site of a wide-host-range plasmid of the Q incompatibility group, and the resulting recombinant plasmid was introduced into Tn5-generated Lac- mutants of Rhizobium meliloti. The R. meliloti transconjugants accumulated lactose about 1,000-fold, equivalent to a proton motive force of -170 to -180 mV, not significantly different from the values calculated from the distributions of weak acids and lipophilic cations.
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15
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Bergersen F, Turner G. Measurement of components of proton motive force and related parameters in steady, microaerobic conditions. J Microbiol Methods 1985. [DOI: 10.1016/0167-7012(85)90003-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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16
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Howard KS, Hales BJ, Socolofsky MD. In vivo interaction between nitrogenase molybdenum-iron protein and membrane in Azotobacter vinelandii and Rhodospirillum rubrum. BIOCHIMICA ET BIOPHYSICA ACTA 1985; 812:575-85. [PMID: 2981550 DOI: 10.1016/0005-2736(85)90333-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Oriented whole cell multilayers of Azotobacter vinelandii and Rhodospirillum rubrum were analyzed by electron spin resonance (ESR) spectroscopy to detect possible structural associations between nitrogenase molybdenum-iron (MoFe) protein and cytoplasmic or intracytoplasmic membrane. Initially, protocols were designed to obtain strong molybdenum-iron protein ESR signals in whole cell samples of each organism. Then, two-dimensional orientation of whole cell membranes was demonstrated in whole cell multilayers using doxyl stearate spin label in A. vinelandii and the bacteriochlorophyll a dimer triplet signal, (BCHl a)T2, from the intracytoplasmic membrane-bound photosynthetic apparatus of R. rubrum. Subsequent analysis of the low-field signals, g = 4.3 and g = 3.6, of molybdenum-iron protein in whole cell multilayers of each organism showed orientation-dependent characteristics, although the properties of each were different. Specifically, as the normal to the membrane plane was rotated from perpendicular to parallel with the ESR magnetic field, the amplitude of the g = 3.6 signal decreased from maximum to about 37% of maximum in A. vinelandii and from maximum to about 88% of maximum in R. rubrum. The angular dependence of the g = 4.3 peak during rotation varied in A. vinelandii, but decreased from maximum to about 63% of maximum in R. rubrum. These data suggest that the molybdenum-iron protein of nitrogenase was oriented in response to the physical orientation of cellular membranes and that a structural association may exist between this nitrogenase component and membrane in these organisms.
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17
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Hellingwerf KJ, Konings WN. The energy flow in bacteria: the main free energy intermediates and their regulatory role. Adv Microb Physiol 1985; 26:125-54. [PMID: 3913291 DOI: 10.1016/s0065-2911(08)60396-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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18
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19
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Ernst A, Böhme H. Control of hydrogen-dependent nitrogenase activity by adenylates and electron flow in heterocysts of Anabaena variabilis (ATCC 29413). BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1984. [DOI: 10.1016/0005-2728(84)90206-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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20
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Gober JW, Kashket ER. H+/ATP stoichiometry of cowpea Rhizobium sp. strain 32H1 cells grown under nitrogen-fixing and nitrogen-nonfixing conditions. J Bacteriol 1984; 160:216-21. [PMID: 6237099 PMCID: PMC214703 DOI: 10.1128/jb.160.1.216-221.1984] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The obligate aerobe Cowpea Rhizobium sp. strain 32H1 in axenic culture is able to fix N2 when grown under 0.2% O2 but not when grown under 21% O2. It was, therefore, of interest to investigate ATP synthesis in these cells grown under the two conditions. When respiring in buffers having pHs ranging from 6 to 8.5, cells grown under either O2 tension maintained an intracellular pH more alkaline than the exterior. The transmembrane chemical gradient of H+ (delta pH) was essentially the same under both conditions of growth, decreasing from ca. 90 mV at medium pH 6 to ca. 30 mV at pH 8.5. However, the transmembrane electrical gradient (delta psi) was significantly higher in cells grown under 21% O2 (150 to 166 mV) than in cells grown under 0.2% O2, the latter being 16 mV at pH 6 and increasing to 88 mV at pH 8.5. Therefore, the proton motive force of 21% O2-grown cells ranged from 237 mV at external pH 6 to 185 mV at pH 8.5, compared with a proton motive force of 114 to 121 mV in the 0.2% O2-grown cells. The cells grown in 0.2% O2 had the same proton motive force whether tested at 21 or at 0.2% O2. The phosphorylation potential, calculated from the intracellular ATP, ADP, and Pi concentrations, was 424 mV in the 21% O2-grown cells and 436 mV in the 0.2% O2-grown cells. Thus, the 21% O2-grown cells translocated 1.8 to 2.3 H+/ATP synthesized by the H+-ATPase, whereas the H+/ATP ratio for 0.2% O2-grown cells was 3.7 to 3.8.
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21
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Haaker H, Wassink H. Electron allocation to H+ and N2 by nitrogenase in Rhizobium leguminosarum bacteroids. EUROPEAN JOURNAL OF BIOCHEMISTRY 1984; 142:37-42. [PMID: 6589160 DOI: 10.1111/j.1432-1033.1984.tb08247.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Electron allocation to H+ and N2 by nitrogenase in intact Rhizobium leguminosarum bacteroids has been studied. Nitrogenase activity was measured in intact cells with succinate and oxygen substrates. When whole cell nitrogenase activity was inhibited by oxygen-limitation or by the addition of the H+-conducting ionophore carbonylcyanide m-chlorophenylhydrazone, both inducing a low intracellular ATP/ADP ratio, the electron allocation to H+ was favoured over that to N2. When whole cell nitrogenase activity was inhibited by excess oxygen or by the addition of the K+-conducting ionophore valinomycin, both inhibiting electron transport to nitrogenase without affecting the intracellular ATP/ADP ratio, no effect upon the electron allocation to H+ and N2 was observed. The whole cell experiments could be confirmed by experiments with bacteroids treated with hexadecyltrimethylammonium bromide. Nitrogenase is highly active in these preparations with Na2S2O4 and MgATP as substrates. No effect was observed upon electron allocation to H+ and N2 when nitrogenase was inhibited by limitation of reductant (Na2S2O4) or MgATP. Only when nitrogenase was inhibited by MgADP, electron allocation to H+ was favoured. The amount of nitrogenase component 1 and 2 in bacteroids was estimated with protein blotting, followed by an immunological detection. It was found that 17% +/- 3% of total bacteroid protein is component 1 and 12% +/- 2% is component 2. The specific nitrogenase activity of bacteroids treated with hexadecyltrimethylammonium bromide is 178 +/- 62 nmol C2H4 formed X min-1 X mg total protein-1. Despite the high protein concentrations, nitrogenase is not inhibited. With cell-free extracts or with purified nitrogenase components isolated from R. leguminosarum bacteroids, electron allocation to H+ was favoured over that to N2, independently of the mechanism of inhibition. The discrepancies between the whole cell studies and those with isolated enzyme will be discussed with respect to the present mechanism of action of nitrogenase.
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22
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Robertson JG, Thomas JE, Gowing LR, Boland MJ. Mg2+ adenosine triphosphatase from cell envelopes of free-living and bacteroid forms of Rhizobium lupini strain NZP2257. Arch Biochem Biophys 1984; 232:337-47. [PMID: 6146293 DOI: 10.1016/0003-9861(84)90549-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
A procedure for the purification of Mg2+ adenosine triphosphatase (EC 3.6.1.3) from free-living and bacteroid forms of Rhizobium lupini NZP2257 is described. The enzyme was released from cell envelopes using Triton X-100 and purified by gel filtration on Ultrogel AcA 22, followed by preparative gel electrophoresis on agarose. The purified ATPase had a molecular weight of about 355,000, as determined from sedimentation coefficients on sucrose gradients. Kinetic analysis of activity of the enzyme from free-living R. lupini showed it to be typical of F1-type Mg2+ ATPases from bacteria. Mg stimulated activity at pH 7.0, although, when present as the free ion, Mg caused non-competitive inhibition (K1 = 1.5 mM). Maximum activity with ATP occurred over a broad pH range from 6.0 to 10.5. ATP, GTP, and UTP, and, to a much lesser degree, CTP and ADP, were hydrolyzed by the enzyme. Hydrolysis of glucose 6-phosphate was not observed. The Km for ATP at pH 7.0 was 0.67 and for GTP 1.4 mM. ATPase activity was inhibited by ADP, and competitive with ATP (KI = 0.18 mM). Azide also caused inhibition but fluoride and DCCD had no effect. Native and sodium dodecyl sulfate-gel electrophoretic analysis revealed no obvious differences between ATPases from free-living and bacteroid forms of R. lupini.
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23
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Schrautemeier B, B�hme H, B�ger P. In vitro studies on pathways and regulation of electron transport to nitrogenase with a cell-free extract from heterocysts of Anabaena variabilis. Arch Microbiol 1984. [DOI: 10.1007/bf00425801] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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24
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Van den Bos RC, Schots A, Hontelez J, Van Kammen A. Constitutive nitrogenase synthesis from de novo transcribed mRNA in isolated Rhizobium leguminosarum bacteroids. ACTA ACUST UNITED AC 1983. [DOI: 10.1016/0167-4781(83)90140-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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25
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Otto R, Brink B, Veldkamp H, Konings WN. The relation between growth rate and electrochemical proton gradient of Streptococcus cremoris. FEMS Microbiol Lett 1983. [DOI: 10.1111/j.1574-6968.1983.tb00261.x] [Citation(s) in RCA: 114] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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26
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Haaker H, Laane C, Hellingwerf K, Houwer B, Konings WN, Veeger C. Short-term regulation of the nitrogenase activity in Rhodopseudomonas sphaeroides. EUROPEAN JOURNAL OF BIOCHEMISTRY 1982; 127:639-45. [PMID: 6983438 DOI: 10.1111/j.1432-1033.1982.tb06920.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The nitrogenase activity in whole cells of Rhodopseudomonas sphaeroides could be inhibited by lowering the electrical potential across the cytoplasmic membrane. The membrane potential was partly dissipated either by lowering the light intensity or by the addition of a lipophilic cation, tetraphenylphosphonium. Under these circumstances, it was shown that the intracellular ATP/ADP ratio was not affected and that the inhibition of the whole cell nitrogenase activity was not due to an inactivation of the nitrogenase enzyme. From these results it is concluded that electron transport to nitrogenase in Rps. sphaeroides is dependent on a high membrane potential. The nitrogenase enzyme in whole cells could be inactivated by lowering the membrane potential across the cytoplasmic membrane by incubating the cells in the dark or in the light in the presence of uncouplers. Nitrogenase could be reactivated in the light in the absence of uncouplers. Some possible mechanisms of action of NH+4 inhibition of whole cell nitrogenase activity could be excluded. Inhibition by NH4Cl of whole cell nitrogenase activity in Rps. sphaeroides could neither be explained by a rapid inactivation of the nitrogenase enzyme, nor by an effect on the intracellular ATP/ADP ratio or the membrane potential. NH+4 inhibits whole cell nitrogenase activity not directly but probably after being assimilated by glutamine synthetase. The role of glutamine, glutamate and 2-oxoglutarate on the regulation of electron transport to nitrogenase will be discussed.
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27
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Hawkesford MJ, Reed RH, Rowell P, Stewart WD. Nitrogenase activity and membrane electrogenesis in the cyanobacterium Plectonema boryanum. EUROPEAN JOURNAL OF BIOCHEMISTRY 1982; 127:63-6. [PMID: 6814911 DOI: 10.1111/j.1432-1033.1982.tb06837.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The relationships between nitrogenase activity (acetylene reduction) and the transplasmalemma proton electrochemical potential gradient (delta muH+) have been investigated using the non-heterocystous filamentous cyanobacterium Plectonema boryanum. By selectively modifying the chemical (delta pH) and electrical (delta psi) components of delta muH+ under conditions in which the size of the ATP pool remained unaffected, nitrogenase activity was found to be dependent on, or regulated by delta psi. When the ATP pool decreased, concomitant with a decreased internal pH (pHi) the requirement for delta psi was modified. The observed reduction in the intracellular ATP pool and the decreased ATP:ADP ratio also correlated with an inhibition of nitrogenase activity. The data are consistent with a model in vivo in which reductant supply to nitrogenase is regulated by, or dependent on an energised plasmalemma and where there is a fine balance between the supply of reductant and ATP for nitrogenase activity. The correlation observed between delta psi and nitrogenase activity extends our previous observations using the heterocystous cyanobacterium Anabaena variabilis.
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28
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Gutschick VP. Energetics of microbial fixation of dinitrogen. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 1982. [DOI: 10.1007/3-540-11019-4_7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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29
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Kashket ER. Effects of aerobiosis and nitrogen source on the proton motive force in growing Escherichia coli and Klebsiella pneumoniae cells. J Bacteriol 1981; 146:377-84. [PMID: 6260744 PMCID: PMC217093 DOI: 10.1128/jb.146.1.377-384.1981] [Citation(s) in RCA: 80] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The electrochemical gradient of hydrogen ions, or proton motive force (PMF), was measured in growing Escherichia coli and Klebsiella pneumoniae in batch culture. The electrical component of the PMF (delta psi) and the chemical component (delta pH) were calculated from the cellular accumulation of radiolabeled tetraphenylphosphonium, thiocyanate, and benzoate ions. In both species, the PMF was constant during exponential phase and decreased as the cells entered stationary phase. Altering the growth rate with different energy substrates had no effect on the PMF. The delta pH (alkaline inside) varied with the pH of the culture medium, resulting in a constant internal pH. During aerobic growth in media at pH 6 to 7, the delta psi was constant at 160 mV (negative inside). The PMF, therefore, was 255 mV in cells growing at pH 6.3, and decreased progressively to 210 mV in pH 7.1 cultures. K. pneumoniae cells and two E. coli strains (K-12 and ML), including a mutant deficient in the H+-translocating ATPase and a pleiotropically energy-uncoupled mutant with a normal ATPase, had the same PMF during aerobic exponential phase. During anaerobic growth, however, both species had delta psi values equal to 0. Therefore, the PMF in anaerobic cells consisted only of the delta pH component, which was 75 mV or less in cells growing at pH 6.2 or greater. These data thus met the expectation that cells deriving metabolic energy from respiration have a PMF above a threshold value of about 200 mV when the ATPase functions in the direction of H+ influx and ATP synthesis; in fermenting cells, a PMF below a threshold value was expected since the enzyme functions in the direction of H+ extrusion and ATP hydrolysis. K. pneumoniae cells growing anaerobically had no delta psi whether the N source added was N2, NH+4 or one of several amino acids; the delta pH was unaffected. Therefore, any energy cost incurred by the process of nitrogen fixation could not be detected as an alteration of the proton gradient.
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30
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Hawkesford MJ, Reed RH, Rowell P, Stewart WD. Nitrogenase activity and membrane electrogenesis in the cyanobacterium Anabaena variabilis Kütz. EUROPEAN JOURNAL OF BIOCHEMISTRY 1981; 115:519-23. [PMID: 6786885 DOI: 10.1111/j.1432-1033.1981.tb06233.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Relationships between nitrogenase activity and individual components of the proton electrochemical potential gradient (delta microH+) in Anabaena variabilis have been investigated. The ionophore nigericin was found to collapse delta pH in favour of the membrane potential (delta psi); hyperpolarization of delta psi was correlated with an increase in nitrogenase activity. A positive relationship between nitrogenase activity and membrane potential was also observed using the ionophore valinomycin and the uncoupler carbonylcyanide m-chlorophenylhydrazone. Furthermore, using the energy transfer inhibitor N,N'-dicyclohexylcarbodiimide, nitrogenase activity appeared to be limited by the supply of reductant rather than ATP. The data suggest, for intact filaments and isolated heterocysts, that delta psi may be important in regulating nitrogenase activity in vivo.
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Effects of the medium composition on the components of the electrochemical proton gradient in Rhodopseudomonas sphaeroides. Arch Microbiol 1981. [DOI: 10.1007/bf00414600] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Carter K, Rawlings J, Orme-Johnson W, Becker R, Evans H. Purification and characterization of a ferredoxin from Rhizobium japonicum bacteroids. J Biol Chem 1980. [DOI: 10.1016/s0021-9258(19)85654-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Laane C, Krone W, Konings W, Haaker H, Veeger C. Short-term effect of ammonium chloride on nitrogen fixation by Azotobacter vinelandii and by bacteroids of Rhizobium leguminosarum. EUROPEAN JOURNAL OF BIOCHEMISTRY 1980; 103:39-46. [PMID: 6928406 DOI: 10.1111/j.1432-1033.1980.tb04286.x] [Citation(s) in RCA: 115] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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