A simple approach was used to identify Rhizobium meliloti DNA regions with the ability to convert a nontransmissible vector into a mobilizable plasmid, i.e., to contain origins of conjugative transfer (oriT, mob). RecA-defective R. meliloti merodiploid populations, where each individual contained a hybrid cosmid from an R. meliloti GR4 gene library, were used as donors en masse in conjugation w...

We have cloned and sequenced the 3-hydroxybutyrate dehydrogenase-encoding gene (bdhA) from Rhizobium (Sinorhizobium) meliloti. The gene has an open reading frame of 777 bp that encodes a polypeptide of 258 amino acid residues (molecular weight 27,177, pI 6.07). The R. meliloti Bdh protein exhibits features common to members of the short-chain alcohol dehydrogenase superfamily. bdhA is the first...

We studied the production of xyloglucanase enzymes of leguminous roots in the presence of Rhizobium and arbuscularmycorrhizal (AM) fungi. The AM fungus Glomus mosseae and Sinorhizobium meliloti GR4 for alfalfa, Rhizobium leguminosarum bv. viceae Rlv 13 for pea, R. leguminosarum bv. trifolii 2152 for clover, R. tropici CIAT 899 for bean and Mesorrhizobium mediterraneum USDA 3392 for chickpea. Th...

FtsZ and FtsA are essential for cell division in Escherichia coli and colocalize to the septal ring. One approach to determine what regions of FtsA and FtsZ are important for their interaction is to identify in vivo interactions between FtsA and FtsZ from different species. As a first step, the ftsA genes of Rhizobium meliloti and Agrobacterium tumefaciens were isolated and characterized. In ad...

The early events in the alfalfa-Rhizobium meliloti symbiosis include deformation of epidermal root hairs and the approximately concurrent stimulation of cell dedifferentiation and cell division in the root inner cortex. These early steps have been studied previously by analysis of R. meliloti mutants. Bacterial strains mutated in nodABC, for example, fail to stimulate either root hair curling o...

The Caulobacter crescentus DNA methyltransferase CcrM (M.CcrMI) methylates the adenine residue in the sequence GANTC. The CcrM DNA methyltransferase is essential for viability, but it does not appear to be part of a DNA restriction-modification system. CcrM homologs are widespread in the alpha subdivision of gram-negative bacteria. We have amplified and sequenced a 258-bp region of the cerM gen...

The ftsZ gene is essential for initiation of cell division in Escherichia coli and Bacillus subtilis. To begin our studies of division arrest during differentiation of Rhizobium meliloti bacteroids, we isolated a R. meliloti ftsZ homolog, ftsZRm. Degenerate primers directed towards a conserved region of ftsZ were used to amplify a segment of R. meliloti DNA by polymerase chain reaction, and the...

Luteolin is a phenolic compound from plants that acts as a potent and specific inducer of nodABC gene expression in Rhizobium meliloti. We have found that R. meliloti RCR2011 exhibits positive chemotaxis towards luteolin. A maximum chemotactic response was observed at 10(-8) M. Two closely related flavonoids, naringenin and apigenin, were not chemoattractants. The presence of naringenin but not...

Siderophores are divided to 2 main structural groups: hydroxamates and catecholates (Drechsel et al. 1995). Hydroxamate siderophores are produced both by bacteria and fungi, while catecholates are reported to the produced only by bacteria (Messenger and Ratledge, 1985). A third group of siderophores the carboxylate (= complexone) type has been reported to be produced exclusively by fungi belong...