Determination of Hydrogenase in Free-living Cultures of <i>Rhizobium japonicum</i> and Energy Efficiency of Soybean Nodules

Lim, S. T.

doi:10.1104/pp.62.4.609

Cited by 66 publications

(26 citation statements)

References 3 publications

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“…B. japonicum can be derepressed for hydrogenase activity if it is placed in an environment which lacks carbon substrates and which is also microaerophilic (10,13). Since hydrogenase is negatively regulated by oxygen, it was potentially a member pf the class of proteins whose synthesis depends on gyrase activity.…”

Section: Resultsmentioning

confidence: 99%

Inhibition of hydrogenase synthesis by DNA gyrase inhibitors in Bradyrhizobium japonicum

Novak¹,

Maier²

1987

J Bacteriol

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Derepression of an uptake hydrogenase in Bradyrhizobium japonicum is dependent on a microaerophilic environment. Addition of DNA gyrase inhibitors during derepression of hydrogenase specifcally prevented expression of the hydrogenase enzyme. Antibodies to individual hydrogenase subunits failed to detect the protein after derepression in the presence of inhibitors, although there was no general inhibition of protein syntbesis. The general pattern of proteins synthesized from 14C-labeled amino acids during derepression was not significantly different whether proteins were labeled in the presence or in the absence of gyrape inhibitors.In contrast, if transcriptiop or translation was inhibited by addition of inhibitors of thowe functions, virtually no proteins were labeled during derepression. This indicated that most of the 14C-labeled proteins were synthesized de novo during derepression, synthesis of most proteins was unaffected by gyrase inhibitors, and the dependence of hydrogenase synthesis on gyrase activity was a specific one.

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Section: Resultsmentioning

confidence: 99%

Inhibition of hydrogenase synthesis by DNA gyrase inhibitors in Bradyrhizobium japonicum

Novak¹,

Maier²

1987

J Bacteriol

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“…Burton of the Nitragin Corp., Milwaukee, Wis. Strain I91 was isolated from nodules of 'Jupiter' soybeans (Gfycine m a ) inoculated with soil 'A' obtained from Shanghai, China. Cultures were checked for uniform colony morphology using a Tween 40 medium (Lim, 1978) followed by repeated streaking for isolated colonies on mannitol/salts/yeast extract (MSY medium) plates containing bromothymol blue (Trinick, 1980;Vincent, 1970) to prevent the isolation of genetically mixed colonies.…”

Section: M Y E L T O N a N D O T H E R S M E T H O D Smentioning

confidence: 99%

“…The relative efficiency (RE) was calculated as RE = 1 -(H, evolution/C,H, reduction) (Schubert & Evans, 1976). Hydrogenase activity was determined by the tritium uptake assay as previously described (Lim, 1978).…”

Section: M Y E L T O N a N D O T H E R S M E T H O D Smentioning

confidence: 99%

Characterization of an Effective Salt-tolerant, Fast-growing Strain of Rhizobium japonicum

et al. 1983

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Rhizobium japonicum USDA191 is a member of a new group of Rhizobium japonicum strains found in China. This strain is one of several strains shown to be salt-tolerant and fast-growing; it is unique in being the only strain of this group that effectively nodulates American soybean cultivars. For these reasons strain USDA 191 was chosen for further study and comparison to the common American Rhizobium japonicum isolate USDA 1 10. Strain USDA 19 1 has a doubling time of 3.2 h in complex medium and grows in concentrations of up to 0.4 M-NaCl, while strain USDAl 10, which has a doubling time of 12 h, is severely inhibited in media containing 0.1 MNaCl. Under salt stress conditions, intracellular levels of K+ and glutamate were shown to increase. A comparison based on carbohydrate metabolism, DNA homology and protein patterns on polyacrylamide gels reveals that strain USDA191 is more closely related to the fastgrowing rhizobia than to Rhizobium japonicum. However, the strain retains capacity to nodulate American soybean and cowpea cultivars effectively.

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“…Conditions have been worked out so that B. japonicum hydrogenase activity can be induced in the free-living form in an H2-and C02-containing atmosphere (16)(17)(18). It is within these controlled circumstances that most hydrogenase regulation studies have been done (16-19, 22, 26, 35, 36).…”

mentioning

confidence: 99%

Common cis-acting region responsible for transcriptional regulation of Bradyrhizobium japonicum hydrogenase by nickel, oxygen, and hydrogen

Kim

Maier

1991

J Bacteriol

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Bradyrhizobiumjaponicum expresses hydrogenase in microaerophilic free-living conditions in the presence of nickel. Plasmid-borne hup-lacZ transcriptional fusion constructs were used to study the regulation of the hydrogenase gene. The hydrogenase gene was transcriptionally induced under microaerobic conditions (0.1 to 3.0% partial pressure 02). The hydrogenase gene was not transcribed or was poorly transcribed in strictly anaerobic conditions or conditions above 3.0% 02. Hydrogen gas at levels as low as 0.1% partial pressure induced hydrogenase transcription, and a high level of transcription was maintained up to at least 10% H2 concentration. No transcription was observed in the absence of H2. Hydrogenase was regulated by H2, 02, and Ni when the 5'-upstream sequence was pared down to include base number -168. However, when the upstream sequence was pared down to base number -118, the regulatory response to 02, H2, and Ni levels was negated. Thus, a common cis-acting regulatory region localized within 50 bp is critical for the regulation of hydrogenase by hydrogen, oxygen, and nickel. As a control, the B. japonicum hemA gene which codes for 8-aminolevulinic acid synthase was also fused to the promoterless lacZ gene, and its regulation was tested in the presence of various concentrations of 02 and H2. hemA-lacZ transcription was not dependent on levels of Ni, 02, or H2. Two different hup-lacZ fusions were tested in a Hup-background, strain JH47; these hup-lacZ constructs in JH47 demonstrated dependency on nickel, 02, and H2, indicating that the hydrogenase protein itself is not a sensor for regulation by 02, H2, or nickel.In soybean root nodules, the Bradyrhizobium japonicum bacterium undergoes a morphological transformation into N2-fixing bacteroids. Within the nodule, conditions are microaerobic because of an 02 diffusion barrier and 02-binding leghemoglobins; because of this, the 02 concentration at the bacteroid surface is estimated to be 11 nM (1). Many new proteins are expressed in the 02-limited nodule environment. In addition to those encoded by the nitrogen fixation genes, a membrane-bound H2-oxidizing hydrogenase enzyme that utilizes the H2 evolved by nitrogenase is expressed. The Ni-containing hydrogenase (3,32,33) activates H2 and sends the electrons through an energy-generating respiratory electron transport chain (reviewed in reference 27). Therefore, it is thought to be a component responsible for maintaining efficient N2 fixation in the nodules.Studying the regulation of bacteroid hydrogenase in response to environmental stimuli supplied to the root nodules is difficult if not physically impossible. Conditions have been worked out so that B. japonicum hydrogenase activity can be induced in the free-living form in an H2-and C02-containing atmosphere (16)(17)(18). It is within these controlled circumstances that most hydrogenase regulation studies have been done (16-19, 22, 26, 35, 36). (30) and 20 bases downstream of it. The transcription initiation site has previously been mapped (30). pBJ3-1 is ...

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Determination of Hydrogenase in Free-living Cultures of Rhizobium japonicum and Energy Efficiency of Soybean Nodules

Cited by 66 publications

References 3 publications

Inhibition of hydrogenase synthesis by DNA gyrase inhibitors in Bradyrhizobium japonicum

Inhibition of hydrogenase synthesis by DNA gyrase inhibitors in Bradyrhizobium japonicum

Characterization of an Effective Salt-tolerant, Fast-growing Strain of Rhizobium japonicum

Common cis-acting region responsible for transcriptional regulation of Bradyrhizobium japonicum hydrogenase by nickel, oxygen, and hydrogen

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