Hydrogen-stimulated CO2fixation and coordinate induction of hydrogenase and ribulosebiphosphate carboxylase in a H2-uptake positive strain ofRhizobium japonicum
✍ Scribed by Frank B. Simpson; Robert J. Maier; Harold J. Evans
- Publisher
- Springer
- Year
- 1979
- Tongue
- English
- Weight
- 907 KB
- Volume
- 123
- Category
- Article
- ISSN
- 0302-8933
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✦ Synopsis
H2-uptake positive strains (122 DES and SR) and Hz-uptake negative strains SR2 and SR3 of Rh&obiurn japonicum were examined for ribulosebisphosphate (RuBP) carboxylase and Hz-uptake activities during growth conditions which induced formation of the hydrogenase system. The rate of 14CO-2 uptake by hydrogenase-derepressed cells was about 6times greater in the presence than in the absence of H 2. RuBP carboxylase activity was observed in flee-living R.japonicum strains 122 DES or SR only when the cells were derepressed for their hydrogenase system. Hydrogenase and RuBP carboxylase activities were coordinately induced by H 2 and both were repressed by added succinate. Hydrogenase-negative mutant strains SR2 and SR 3 derived from R.japonicum SR showed no detectable RuBP carboxylase activities under hydrogenase derepression conditions. No detectable RuBP carboxylase was observed in bacteroids formed by H 2uptake positive strains R. japonicum 122 DES or SR.
Propionyl CoA carboxylase activity was consistently observed in extracts of cells from flee-living cultures of R. japonicum but activity was not appreciably influenced by the addition of H 2. Neither phosphoenolpyruvate carboxylase nor phosphoenolpyruvate carboxykinase activity was detected in extracts of R.
japonicum.