The Electron Transfer Flavoprotein fixABCX Gene Products from Azospirillum brasilense Show a NifA-Dependent Promoter Regulation

Sperotto, Raul Antônio; Gross, Jeferson; Vedoy, Cleber Giovane; Passaglia, Luciane Maria Pereira; Schrank, Irene Silveira

doi:10.1007/s00284-004-4318-3

Cited by 16 publications

(12 citation statements)

References 35 publications

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“…nifQ (AZL010780) was located at a distance from above other nif gene clusters. The fixABCX (AZL006470–AZL006500) cluster, which encoded components participating in the transport of electrons to nitrogenase, 44,45 was adjacent to the nifWVSU cluster and in an opposite orientation (Fig. 2A).…”

Section: Resultsmentioning

confidence: 99%

Complete Genomic Structure of the Cultivated Rice Endophyte Azospirillum sp. B510

Kaneko¹,

Minamisawa²,

Isawa³

et al. 2010

DNA Research

147

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We determined the nucleotide sequence of the entire genome of a diazotrophic endophyte, Azospirillum sp. B510. Strain B510 is an endophytic bacterium isolated from stems of rice plants (Oryza sativa cv. Nipponbare). The genome of B510 consisted of a single chromosome (3 311 395 bp) and six plasmids, designated as pAB510a (1 455 109 bp), pAB510b (723 779 bp), pAB510c (681 723 bp), pAB510d (628 837 bp), pAB510e (537 299 bp), and pAB510f (261 596 bp). The chromosome bears 2893 potential protein-encoding genes, two sets of rRNA gene clusters (rrns), and 45 tRNA genes representing 37 tRNA species. The genomes of the six plasmids contained a total of 3416 protein-encoding genes, seven sets of rrns, and 34 tRNAs representing 19 tRNA species. Eight genes for plasmid-specific tRNA species are located on either pAB510a or pAB510d. Two out of eight genomic islands are inserted in the plasmids, pAB510b and pAB510e, and one of the islands is inserted into trnfM-CAU in the rrn located on pAB510e. Genes other than the nif gene cluster that are involved in N2 fixation and are homologues of Bradyrhizobium japonicum USDA110 include fixABCX, fixNOQP, fixHIS, fixG, and fixLJK. Three putative plant hormone-related genes encoding tryptophan 2-monooxytenase (iaaM) and indole-3-acetaldehyde hydrolase (iaaH), which are involved in IAA biosynthesis, and ACC deaminase (acdS), which reduces ethylene levels, were identified. Multiple gene-clusters for tripartite ATP-independent periplasmic-transport systems and a diverse set of malic enzymes were identified, suggesting that B510 utilizes C4-dicarboxylate during its symbiotic relationship with the host plant.

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Section: Resultsmentioning

confidence: 99%

Complete Genomic Structure of the Cultivated Rice Endophyte Azospirillum sp. B510

Kaneko¹,

Minamisawa²,

Isawa³

et al. 2010

DNA Research

147

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“…This evidence is corroborated by reports showing that the operon fixABCX is regulated by the NifA protein in A. brasilense and Rhizobium spp. [34-36]. …”

Section: Resultsmentioning

confidence: 99%

Genomic insights into the versatility of the plant growth-promoting bacterium Azospirillum amazonense

et al. 2011

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BackgroundThe species Azospirillum amazonense belongs to a well-known genus of plant growth-promoting bacteria. This bacterium is found in association with several crops of economic importance; however, there is a lack of information on its physiology. In this work, we present a comprehensive analysis of the genomic features of this species.ResultsGenes of A. amazonense related to nitrogen/carbon metabolism, energy production, phytohormone production, transport, quorum sensing, antibiotic resistance, chemotaxis/motility and bacteriophytochrome biosynthesis were identified. Noteworthy genes were the nitrogen fixation genes and the nitrilase gene, which could be directly implicated in plant growth promotion, and the carbon fixation genes, which had previously been poorly investigated in this genus. One important finding was that some A. amazonense genes, like the nitrogenase genes and RubisCO genes, were closer phylogenetically to Rhizobiales members than to species of its own order.ConclusionThe species A. amazonense presents a versatile repertoire of genes crucial for its plant-associated lifestyle.

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“…Additionally, nifA helps regulate the expression of various nif genes [74], while fixC is part of the fixABCX complex involved in gene transcription regulation in low oxygen conditions (e.g. inside the nodule) and is posited to have a central role in electron transfer to nitrogenase [75,76]. In general, nod genes code for enzymes that generate Nod factors, rhizobium signalling molecules between rhizobia and plant required for nodulation initiation; nodB in particular is part of the nodABC operon, which generates the main Nod factor structure [24].…”

Section: (C) Potential Functions Of Key Candidate Genesmentioning

confidence: 99%

Ecological genomics of mutualism decline in nitrogen-fixing bacteria

2016

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Anthropogenic changes can influence mutualism evolution; however, the genomic regions underpinning mutualism that are most affected by environmental change are generally unknown, even in well-studied model mutualisms like the interaction between legumes and their nitrogen (N)-fixing rhizobia. Such genomic information can shed light on the agents and targets of selection maintaining cooperation in nature. We recently demonstrated that N-fertilization has caused an evolutionary decline in mutualistic partner quality in the rhizobia that form symbiosis with clover. Here, population genomic analyses of N-fertilized versus control rhizobium populations indicate that evolutionary differentiation at a key symbiosis gene region on the symbiotic plasmid (pSym) contributes to partner quality decline. Moreover, patterns of genetic variation at selected loci were consistent with recent positive selection within N-fertilized environments, suggesting that N-rich environments might select for less beneficial rhizobia. By studying the molecular population genomics of a natural bacterial population within a long-term ecological field experiment, we find that: (i) the N environment is indeed a potent selective force mediating mutualism evolution in this symbiosis, (ii) natural variation in rhizobium partner quality is mediated in part by key symbiosis genes on the symbiotic plasmid, and (iii) differentiation at selected genes occurred in the context of otherwise recombining genomes, resembling eukaryotic models of adaptation.

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The Electron Transfer Flavoprotein fixABCX Gene Products from Azospirillum brasilense Show a NifA-Dependent Promoter Regulation

Cited by 16 publications

References 35 publications

Complete Genomic Structure of the Cultivated Rice Endophyte Azospirillum sp. B510

Complete Genomic Structure of the Cultivated Rice Endophyte Azospirillum sp. B510

Genomic insights into the versatility of the plant growth-promoting bacterium Azospirillum amazonense

Ecological genomics of mutualism decline in nitrogen-fixing bacteria

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