We have previously demonstrated that the nifA promoter (nifAp) of Rhizobium meliloti is inducible under microaerobic conditions in the absence of alfalfa. Here we show that microaerobic activation of nifAp involves both cis- and trans-acting regulatory controls identical to those used symbiotically. The start site for nifA mRNA synthesis was found to be the same during symbiosis and microaerobiosis, and a deletion analysis of nifAp demonstrated that DNA between positions -62 and -45 is essential for induction. Mutants isolated as being unable to induce nifA microaerobically also were found to be defective in symbiotic nitrogen fixation with alfalfa. Such mutants form nodules that are equivalent cytologically to those induced by nifA::Tn5 mutants. Genetic and structural studies have localized the mutations to a cluster of fix genes 200 kilobases distant from the nod-nif region on the pSym megaplasmid [Renalier, M.-H., Batut, J., Ghai, J., Terzaghi, B., Gherardi, M., David, M., Garnerone, A.-M., Vasse, J., Truchet, G., Huguet, T. & Boistard, P. (1987) J. Bacteriol. 169, 2231-2238].
Download full-text PDF |
Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC280143 | PMC |
| http://dx.doi.org/10.1073/pnas.85.9.3062 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
The Complex Epigenetic Panorama in the Multipartite Genome of the Nitrogen-Fixing Bacterium Sinorhizobium meliloti.
Genome Biol Evol
January 2025
Department of Biology, University of Florence, 50019 Sesto Fiorentino, Italy.
In prokaryotes, DNA methylation plays roles in DNA repair, gene expression, cell cycle progression, and immune recognition of foreign DNA. Genome-wide methylation patterns can vary between strains, influencing phenotype, and gene transfer. However, broader evolutionary studies on bacterial epigenomic variation remain limited.
View Article and Find Full Text PDFReplacement of the essential catalytic aspartate with serine leads to an active form of copper-containing nitrite reductase from the denitrifier Sinorhizobium meliloti 2011.
Biochim Biophys Acta Proteins Proteom
December 2024
Departamento de Física, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral and CONICET, S3000ZAA Santa Fe, Argentina.
Article Synopsis
- The study details the characterization of a mutated variant of copper-containing nitrite reductase (SmNirK) from S. meliloti, where the catalytic aspartate (Asp) is replaced with serine (Ser) via site-directed mutagenesis.
- The D134S variant retains the homotrimer structure and similar T1 electron transfer center to the wild-type, but shows altered electronic properties in the T2 active site, impacting its enzymatic efficiency and pH dependence.
- EPR studies reveal significant changes in the T2 properties due to the mutation, highlighting the role of T2 ligands in catalysis and suggesting a potential mechanism for electron transfer influenced by the Asp/Ser switch.
Biosynthesis of Phenolic Compounds of After Inoculation with Selected PGPR Strains.
Int J Mol Sci
November 2024
Institute of Biology, University of Szczecin, Wąska 13, 71-415 Szczecin, Poland.
The phenylpropanoid biosynthesis pathway is involved in the response of plants to stress factors, including microorganisms. This paper presents how free-living strains of rhizobacteria KK5, KK7, KK4, and the symbiotic strain KK13 affect the expression of genes encoding phenylalanine ammonia-lyase (PAL), the activity of this enzyme, and the production of phenolic compounds in . Seedlings were inoculated with rhizobacteria, then at T0, T24, T72, and T168 after inoculation, the leaves and roots were analyzed for gene expression, enzyme activity, and the content of phenolic compounds.
View Article and Find Full Text PDFThe low enoyl-acyl carrier protein reductase activity of FabI2 is responsible for the high unsaturated fatty acid composition in Sinorhizobium meliloti.
BMC Microbiol
December 2024
Guangdong Provincial Key Laboratory for the Development Biology and Environmental Adaptation of Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou, Guangdong, 510642, China.
Background: Sinorhizobium meliloti is noted for its exceptional capacity to produce unsaturated fatty acids (UFAs). Earlier studies have indicated that S. meliloti primarily employs the FabA-FabB pathway for UFA synthesis, however, the mechanisms remain elusive.
View Article and Find Full Text PDFMicrobes display broad diversity in cobamide preferences.
bioRxiv
November 2024
Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA 94720, U.S.A.
Cobamides, the vitamin B (cobalamin) family of cofactors, are used by most organisms but produced by only a fraction of prokaryotes, and are thus considered key shared nutrients among microbes. Cobamides are structurally diverse, with multiple different cobamides found in most microbial communities. The ability to use different cobamides has been tested for several bacteria and microalgae, and nearly all show preferences for certain cobamides.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!