The RNA Polymerase Subunit from Sinorhizobium meliloti Can Assemble with RNA Polymerase Subunits from Escherichia coli and Function in Basal and Activated Transcription both In Vivo and In Vitro Melicent C. Peck, Tamas Gaal, Robert F. Fisher, Richard L. Gourse, and Sharon R. Long* Department of Biological Sciences, Stanford University, Stanford, California 94305, and Department of Bacteriology,...

Expression of the inner membrane protein FoxB (PA2465) of Pseudomonas aeruginosa in mutants of Sinorhizobium meliloti that are defective in the utilization of ferrichrome, ferrioxamine B, and schizokinen resulted in the restoration of siderophore utilization. Mutagenesis of foxB in P. aeruginosa did not abolish siderophore utilization, suggesting that the function is redundant.

We have cloned the nodFE operon from Sinorhizobium sp. strain MUS10. MUS10 NodF shows sequence homology to acyl carrier protein and enables an S. meliloti nodF mutant to effectively nodulate alfalfa. Our results demonstrate the occurrence of nodFE in a symbiont that nodulates a legume host not belonging to the galegoid group.

Nodulation of alfalfa by exoB mutants of Rhizobium meliloti occurred without root hair curling or infection thread formation. nod exoB double mutants had the same nodulation deficiency as single nod mutants. Therefore, all the known nod genes are involved in nodule induction by exoB mutants, which apparently occurs via intercellular invasion.

Sinorhizobium meliloti hpdA, which encodes the herbicide target 4-hydroxyphenylpyruvate dioxygenase, is positively regulated by HpdR. Gel mobility shift and DNase I footprinting analyses revealed that HpdR binds to a region that spans two conserved direct-repeat sequences within the hpdR-hpdA intergenic space. HpdR-dependent hpdA transcription occurs in the presence of 4-hydroxyphenylpyruvate, ...

Employing a novel two-part screen, we identified Sinorhizobium meliloti mutants that were both sensitive to hydrogen peroxide and symbiotically defective on the host plant Medicago sativa. The mutations affect a wide variety of cellular processes and represent both novel and previously identified genes important in symbiosis.

The role of glycine betaine and choline in osmoprotection of various Rhizobium, Sinorhizobium, Mesorhizobium, Agrobacterium, and Bradyrhizobium reference strains which display a large variation in salt tolerance was investigated. When externally provided, both compounds enhanced the growth of Rhizobium tropici, Sinorhizobium meliloti, Sinorhizobium fredii, Rhizobium galegae, Agrobacterium tumef...

An intracellular plant pathogen 'Candidatus Liberibacter asiaticus,' a member of the Rhizobiales, is related to Sinorhizobium meliloti, Bradyrhizobium japonicum, nitrogen fixing endosymbionts, Agrobacterium tumefaciens, a plant pathogen, and Bartonella henselae, an intracellular mammalian pathogen. Whole chromosome comparisons identified at least 50 clusters of conserved orthologous genes found...

Transformation of R factor RP4 and its derivative pRK290 from Escherichia coli to Rhizobium meliloti is reported. The efficiency of transformation was in the range of 10(-5) per viable cell. In addition, chromosomal DNA prepared from one R. meliloti strain resistant to streptomycin was transferred to the isoleucine-valine-requiring mutant susceptible to streptomycin.

Sinorhizobium meliloti was isolated from nodules and soil from western Tajikistan, a center of diversity of the host plants (Medicago, Melilotus, and Trigonella species). There was evidence of recombination, but significant disequilibrium, between and within the chromosome and megaplasmids. The most frequent alleles matched those in the published genome sequence.