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A Rhizobium leguminosarum bv. viciae VF39 gene (gabT) encoding a gamma-aminobutyrate (GABA) aminotransferase was identified, cloned and characterized. This gene is thought to be involved in GABA metabolism via the GABA shunt pathway, a theoretical bypass of the 2-oxoglutarate dehydrogenase complex. Mutants in gabT are still able to grow on GABA as a sole(More)
The ultimate objective of PhIMED, in which two European (Germany, Italy) and two Mediterranean (Morocco, Egypt) countries collaborate, is to improve the cultivation of French bean (Phaseolus vulgaris) under arid and semi-arid conditions by analysing and enhancing stress tolerance of the nitrogen fixing rhizobial microsymbionts. Rhizobial strains nodulating(More)
A gene from Rhizobium meliloti coding for an adenylate cyclase was sequenced, and the deduced protein sequence was compared with those of other known adenylate cyclases. No similarity could be detected with the procaryotic counterparts. However, striking similarity was found with the catalytic region of Saccharomyces cerevisiae adenylate cyclase, the(More)
The stability of the thy autoselective system, based on an essential thymidylate synthase gene, for enhanced maintenance of plasmid vectors in Rhizobium meliloti was evaluated in the greenhouse and with field-grown alfalfa. The thy autoselective system consists of a free-replicating, broad-host-range plasmid vector containing a copy of the thyA gene from(More)
A second adenylate cyclase (cya2) gene was isolated from a Rhizobium meliloti F34 gene bank. Complemented E. coli delta cya mutants were capable of utilizing a number of, but not all, carbon sources known to be regulated by cAMP. DNA hybridization studies showed cya2 to be unique to R. meliloti strains. The cya2 nucleotide sequence was determined and found(More)
In this report, the expression of late symbiotic genes (fnrN, fixN, and nifA) of Rhizobium leguminosarum bv. viciae was studied in nodules of mutant pea lines blocked at four successive stages of nodule development. Bacterial gene expression was analyzed in situ with transcriptional gusA reporter gene fusions. As a control, a constitutively expressed gusA(More)
The genes controlling the transport of C4-dicarboxylic acids from Rhizobium meliloti have been cloned and analysed. The nucleotide sequence of the control region of the structural dctA and the regulatory dctBD genes has been determined. Comparison with the Rhizobium leguminosarum dct genes revealed a high degree of homology. Gene fusions to the enteric(More)
The Rhizobium leguminosarum bv. viciae VF39 FixL protein belongs to a distinct group of hybrid regulatory sensor proteins that bear a covalently linked C-terminal receiver domain. FixL has an unorthodox histidine kinase domain, which is shared with many other hybrid regulators. The purified FixL protein had autophosphorylation activity. A truncated protein,(More)
The gene products of the Rhizobium meliloti dctB and dctD genes, which control the expression of the C4-dicarboxylic acid transporter DctA, were overproduced in Escherichia coli and purified. The purified sensor protein, DctB, was shown to have autophosphorylation activity in vitro and could subsequently phosphorylate the transcriptional activator, DctD.(More)