Dataset Information

Characterization of the NifA-RpoN regulon in Rhizobium etli in free life and in symbiosis with Phaseolus vulgaris.

ABSTRACT: The NifA-RpoN complex is a master regulator of the nitrogen fixation genes in alphaproteobacteria. Based on the complete Rhizobium etli genome sequence, we constructed an R. etli CFN42 oligonucleotide (70-mer) microarray and utilized this tool, reverse transcription (RT)-PCR analysis (transcriptomics), proteomics, and bioinformatics to decipher the NifA-RpoN regulon under microaerobic conditions (free life) and in symbiosis with bean plants. The R. etli NifA-RpoN regulon was determined to contain 78 genes, including the genes involved in nitrogen fixation, and the analyses revealed 42 new NifA-RpoN-dependent genes. More importantly, this study demonstrated that the NifA-RpoN regulon is composed of genes and proteins that have very diverse functions, that play fundamental and previously less appreciated roles in regulating the normal physiology of the cell, and that have important functions in providing adequate conditions for efficient nitrogen fixation in symbiosis. The R. etli NifA-RpoN regulon defined here has some components in common with other NifA-RpoN regulons described previously, but the vast majority of the components have been found only in the R. etli regulon, suggesting that they have a specific role in this bacterium and particular requirements during nitrogen fixation compared with other symbiotic bacterial models.

SUBMITTER: Salazar E

PROVIDER: S-EPMC2897426 | biostudies-other | 2010 Jul

REPOSITORIES: biostudies-other

ACCESS DATA

Publications

Characterization of the NifA-RpoN regulon in Rhizobium etli in free life and in symbiosis with Phaseolus vulgaris.

Salazar Emmanuel E Díaz-Mejía J Javier JJ Moreno-Hagelsieb Gabriel G Martínez-Batallar Gabriel G Mora Yolanda Y Mora Jaime J Encarnación Sergio S

Applied and environmental microbiology 20100507 13

The NifA-RpoN complex is a master regulator of the nitrogen fixation genes in alphaproteobacteria. Based on the complete Rhizobium etli genome sequence, we constructed an R. etli CFN42 oligonucleotide (70-mer) microarray and utilized this tool, reverse transcription (RT)-PCR analysis (transcriptomics), proteomics, and bioinformatics to decipher the NifA-RpoN regulon under microaerobic conditions (free life) and in symbiosis with bean plants. The R. etli NifA-RpoN regulon was determined to contai ...[more]

PMID: 20453139

Similar Datasets

Project description:The rpoN region of Rhizobium etli was isolated by using the Bradyrhizobium japonicum rpoN1 gene as a probe. Nucleotide sequence analysis of a 5,600-bp DNA fragment of this region revealed the presence of four complete open reading frames (ORFs), ORF258, rpoN, ORF191, and ptsN, coding for proteins of 258, 520, 191, and 154 amino acids, respectively. The gene product of ORF258 is homologous to members of the ATP-binding cassette-type permeases. ORF191 and ptsN are homologous to conserved ORFs found downstream from rpoN genes in other bacterial species. Unlike in most other microorganisms, rpoN and ORF191 are separated by approximately 1.6 kb. The R. etli rpoN gene was shown to control in free-living conditions the production of melanin, the activation of nifH, and the metabolism of C4-dicarboxylic acids and several nitrogen sources (ammonium, nitrate, alanine, and serine). Expression of the rpoN gene was negatively autoregulated and occurred independently of the nitrogen source. Inactivation of the ptsN gene resulted in a decrease of melanin synthesis and nifH expression. In a search for additional genes controlling the synthesis of melanin, an R. etli mutant carrying a Tn5 insertion in ptsA, a gene homologous to the Escherichia coli gene coding for enzyme I of the phosphoenolpyruvate:sugar phosphotransferase system, was obtained. The R. etli ptsA mutant also displayed reduced expression of nifH. The ptsN and ptsA mutants also displayed increased sensitivity to the toxic effects of malate and succinate. Growth of both mutants was inhibited by these C4-dicarboxylates at 20 mM at pH 7.0, while wild-type cells grow normally under these conditions. The effect of malate occurred independently of the nitrogen source used. Growth inhibition was decreased by lowering the pH of the growth medium. These results suggest that ptsN and ptsA are part of the same regulatory cascade, the inactivation of which renders the cells sensitive to toxic effects of elevated concentrations of malate or succinate.

Dataset Information

Characterization of the NifA-RpoN regulon in Rhizobium etli in free life and in symbiosis with Phaseolus vulgaris.

Publications

Characterization of the NifA-RpoN regulon in Rhizobium etli in free life and in symbiosis with Phaseolus vulgaris.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets