Karin Nadler

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The obligately aerobic soybean root nodule bacterium Rhizobium japonicum produces large amounts of heme (iron protoporphyrin) only under low oxygen tensions, such as exist in the symbiotic root nodule. Aerobically incubated suspensions of both laboratory-cultured and symbiotic bacteria (bacteroids) metabolize delta-aminolevulinic acid to uroporphyrin,(More)
Iron acquisition by symbiotic Rhizobium spp. is essential for nitrogen fixation in the legume root nodule symbiosis. Rhizobium leguminosarum 116, an ineffective mutant strain with a defect in iron acquisition, was isolated after nitrosoguanidine mutagenesis of the effective strain 1062. The pop-1 mutation in strain 116 imparted to it a complex phenotype,(More)
During nodulation of soybean (Glycine max) by Rhizobium japonicum, variations in the activities of two enzymes of heme biosynthesis, delta-aminolevulinic acid synthase (ALAS) and delta-aminolevulinic acid dehydrase (ALAD) are described. delta-Aminolevulinic acid synthase activity is found in the bacteroid fraction of nodules, but is not detected in the(More)
The effects of iron deficiency on heme biosynthesis in Rhizobium japonicum were examined. Iron-deficient cells had a decreased maximum cell yield and a decreased cytochrome content and excreted protoporphyrin into the growth medium. The activities of the first two enzymes of heme biosynthesis, delta-aminolevulinic acid synthase (EC 2.3.1.37) and(More)
Cultures of Rhizobium japonicum were grown with vigorous aeration to stationary phase and were then incubated under restricted aeration for several days. Under these "microaerobic" conditions, cellular heme content increased 10-fold, and visible amounts of porphyrins were released into the culture medium. The two predominant porphyrins produced were(More)
In 7- to 10-day-old leaves of etiolated barley (Hordeum vulgare), all of the enzymes that convert delta-aminolevulinic acid to chlorophyll are nonlimiting during the first 6 to 12 hours of illumination, even in the presence of inhibitors of protein synthesis. The limiting activity for chlorophyll synthesis appears to be a protein (or proteins) related to(More)