Aspartate aminotransferase activity is required for aspartate catabolism and symbiotic nitrogen fixation in Rhizobium meliloti
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چکیده
منابع مشابه
A phosphate transport system is required for symbiotic nitrogen fixation by Rhizobium meliloti.
The bacterium Rhizobium meliloti forms N2-fixing root nodules on alfalfa plants. The ndvF locus, located on the 1,700-kb pEXO megaplasmid of R. meliloti, is required for nodule invasion and N2 fixation. Here we report that ndvF contains four genes, phoCDET, which encode an ABC-type transport system for the uptake of Pi into the bacteria. The PhoC and PhoD proteins are homologous to the Escheric...
متن کاملRhizobium meliloti genes required for C4-dicarboxylate transport and symbiotic nitrogen fixation are located on a megaplasmid.
A mutant of Rhizobium meliloti unable to transport C4 dicarboxylates (dct) was isolated after Tn5 mutagenesis. The mutant, 4F6, could not grow on aspartate or the tricarboxylic acid cycle intermediates succinate, fumarate, or malate. It produced symbiotically ineffective nodules on Medicago sativa in which bacteroids appeared normal, but the symbiotic zone was reduced and the plant cells contai...
متن کاملRelative Efficacy of Different Alfalfa Cultivar-Rhizobium meliloti Strain Combinations for Symbiotic Nitrogen Fixation.
Five Rhizobium meliloti isolates known to have different capabilities for expression of nitrogenase activity under symbiotic conditions were used to inoculate four representative Medicago sativa cultivars under aseptic conditions. Nitrogenase activities and respiratory activity were measured for whole plants and excised nodules. Dry weights and nodule numbers were also recorded after 4 weeks of...
متن کاملDirected transposon Tn5 mutagenesis and complementation analysis of Rhizobium meliloti symbiotic nitrogen fixation genes.
An 18 kb region adjacent to and surrounding the genes for nitrogenase (nif) was cloned from the genome of the symbiotic nitrogen-fixing species Rhizobium meliloti. A total of 31 Tn5 insertions in the nif region were constructed and assayed for their effect on symbiotic nitrogen fixation (Fix phenotype). Fix- insertions were found in two clusters, one 6.3 kb region not containing essential symbi...
متن کاملClustering of nitrogen fixation (nif) genes in Rhizobium meliloti.
A cloned 17.3-kilobase region of the Rhizobium meliloti genome with homology to the Klebsiella pneumoniae nitrogenase structural genes was studied. Limits on the extent of homology were determined. Transposon mutagenesis of this region of the genome verified that it contained functional nif genes, Some transposon insertions resulted in a defective symbiotic phenotype, whereas others had no noti...
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ژورنال
عنوان ژورنال: Journal of Bacteriology
سال: 1991
ISSN: 0021-9193,1098-5530
DOI: 10.1128/jb.173.9.2879-2887.1991