Polyamine biosynthesis and biological roles in rhizobia

2019 ◽  
Vol 366 (7) ◽  
Author(s):  
Victor A Becerra-Rivera ◽  
Michael F Dunn
Keyword(s):  
Stress Resistance ◽  
Biofilm Formation ◽  
Sinorhizobium Meliloti ◽  
Growth Stress ◽  
Nitrogen Fixing ◽  
Amino Groups ◽  
Nitrogen Fixing Bacteria ◽  
Polyamine Biosynthesis ◽  
Exopolysaccharide Production

ABSTRACTPolyamines are ubiquitous molecules containing two or more amino groups that fulfill varied and often essential physiological and regulatory roles in all organisms. In the symbiotic nitrogen-fixing bacteria known as rhizobia, putrescine and homospermidine are invariably produced while spermidine and norspermidine synthesis appears to be restricted to the alfalfa microsymbiont Sinorhizobium meliloti. Studies with rhizobial mutants deficient in the synthesis of one or more polyamines have shown that these compounds are important for growth, stress resistance, motility, exopolysaccharide production and biofilm formation. In this review, we describe these studies and examine how polyamines are synthesized and regulated in rhizobia.

scholarly journals Novel Genes and Regulators That Influence Production of Cell Surface Exopolysaccharides inSinorhizobium meliloti

2017 ◽  
Vol 200 (3) ◽  
Author(s):  
Melanie J. Barnett ◽  
Sharon R. Long
Keyword(s):  
Cell Surface ◽  
Biofilm Formation ◽  
Sinorhizobium Meliloti ◽  
Developmental Process ◽  
Root Nodules ◽  
Critical Role ◽  
Nitrogen Fixing ◽  
Symbiotic Interaction ◽  
Content Type ◽  
Mutant Phenotypes

ABSTRACTSinorhizobium melilotiis a soil-dwelling alphaproteobacterium that engages in a nitrogen-fixing root nodule symbiosis with leguminous plants. Cell surface polysaccharides are important both for adapting to stresses in the soil and for the development of an effective symbiotic interaction. Among the polysaccharides characterized to date, the acidic exopolysaccharides I (EPS-I; succinoglycan) and II (EPS-II; galactoglucan) are particularly important for protection from abiotic stresses, biofilm formation, root colonization, and infection of plant roots. Previous genetic screens discovered mutants with impaired EPS production, allowing the delineation of EPS biosynthetic pathways. Here we report on a genetic screen to isolate mutants with mucoid colonial morphologies that suggest EPS overproduction. Screening with Tn5-110, which allows the recovery of both null and upregulation mutants, yielded 47 mucoid mutants, most of which overproduce EPS-I; among the 30 unique genes and intergenic regions identified, 14 have not been associated with EPS production previously. We identified a new protein-coding gene,emmD, which may be involved in the regulation of EPS-I production as part of the EmmABC three-component regulatory circuit. We also identified a mutant defective in EPS-I production, motility, and symbiosis, where Tn5-110 was not responsible for the mutant phenotypes; these phenotypes result from a missense mutation inrpoAcorresponding to the domain of the RNA polymerase alpha subunit known to interact with transcription regulators.IMPORTANCEThe alphaproteobacteriumSinorhizobium meliloticonverts dinitrogen to ammonium while inhabiting specialized plant organs termed root nodules. The transformation ofS. melilotifrom a free-living soil bacterium to a nitrogen-fixing plant symbiont is a complex developmental process requiring close interaction between the two partners. As the interface between the bacterium and its environment, theS. meliloticell surface plays a critical role in adaptation to varied soil environments and in interaction with plant hosts. We isolated and characterizedS. melilotimutants with increased production of exopolysaccharides, key cell surface components. Our diverse set of mutants suggests roles for exopolysaccharide production in growth, metabolism, cell division, envelope homeostasis, biofilm formation, stress response, motility, and symbiosis.

Exopolysaccharide production by nitrogen-fixing bacteria within nodules of Medicago plants exposed to chronic radiation in the Chernobyl exclusion zone

2010 ◽  
Vol 161 (2) ◽  
pp. 101-108 ◽  
Author(s):  
Nathalie Pawlicki-Jullian ◽  
Bernard Courtois ◽  
Michelle Pillon ◽  
David Lesur ◽  
Anne Le Flèche-Mateos ◽  
...  
Keyword(s):  
Nitrogen Fixing ◽  
Exclusion Zone ◽  
Nitrogen Fixing Bacteria ◽  
Exopolysaccharide Production ◽  
Chronic Radiation

GENOME WIDE IDENTIFICATION OF DNA BINDING MOTIFS OF NodD-FACTOR IN SINORHIZOBIUM MELILOTI AND MESORHIZOBIUM LOTI

2005 ◽  
Vol 03 (04) ◽  
pp. 773-801 ◽  
Author(s):  
FEROZ KHAN ◽  
SHIPRA AGARWAL ◽  
B. N. MISHRA
Keyword(s):  
Dna Binding ◽  
Sinorhizobium Meliloti ◽  
Consensus Sequence ◽  
Nitrogen Fixing ◽  
Nitrogen Fixing Bacteria ◽  
Model Legume ◽  
Binding Motifs ◽  
Mesorhizobium Loti ◽  
Genome Wide ◽  
Dna Binding Motifs

NodD transcription factor is a regulatory protein of nitrogen fixing bacteria, which activates expression of nod genes participating in nodulation during interaction with its symbiont legumes. It's DNA binding motifs have been characterized and reported in Sinorhizobium meliloti and this pattern information has been used in our theoretical analyses to detect its novel regulated genes in genomes of S. meliloti and Mesorhizobium loti. M. loti, a symbiont to model legume plant Lotus japonicus, showed presence of these regulatory motifs in upstream sequences of nod and other functionally related genes. The methodology involved comparative potential weight matrix construction through GIBBS SAMPLER (RSAT) and MEME tools, using information of conserved upstream sequences of nine genes including nod and neighboring genes of both genomes possessing nod-box like motif. The resultant DNA consensus sequence had highly conserved nod-box like 17 bp long motif consensus sequence pattern for binding of detected NodD transcription factors as analyzed by homologous clustering method and therefore the genome wide predictions were considered highly accurate since confirmed by operon delineation method and the described methodology can be used in other nitrogen fixing bacteria to pursue the study in detail.

scholarly journals Cowpea symbiotic efficiency, pH and aluminum tolerance in nitrogen-fixing bacteria

2014 ◽  
Vol 71 (3) ◽  
pp. 171-180 ◽  
Author(s):  
Bruno Lima Soares ◽  
Paulo Avelar Ademar Ferreira ◽  
Silvia Maria de Oliveira-Longatti ◽  
Leandro Marciano Marra ◽  
Marcia Rufini ◽  
...  
Keyword(s):  
Aluminum Tolerance ◽  
Nitrogen Fixing ◽  
Nitrogen Fixing Bacteria ◽  
Symbiotic Efficiency

scholarly journals Genomic characterization and computational phenotyping of nitrogen-fixing bacteria isolated from Colombian sugarcane fields

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Luz K. Medina-Cordoba ◽  
Aroon T. Chande ◽  
Lavanya Rishishwar ◽  
Leonard W. Mayer ◽  
Lina C. Valderrama-Aguirre ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Nitrogen Fixation ◽  
Plant Growth ◽  
Phosphate Solubilization ◽  
Nitrogen Fixing ◽  
Nitrogen Fixing Bacteria ◽  
Promising Tool ◽  
A Genome ◽  
Plant Growth Promoting ◽  
Growth Promoting

AbstractPrevious studies have shown the sugarcane microbiome harbors diverse plant growth promoting microorganisms, including nitrogen-fixing bacteria (diazotrophs), which can serve as biofertilizers. The genomes of 22 diazotrophs from Colombian sugarcane fields were sequenced to investigate potential biofertilizers. A genome-enabled computational phenotyping approach was developed to prioritize sugarcane associated diazotrophs according to their potential as biofertilizers. This method selects isolates that have potential for nitrogen fixation and other plant growth promoting (PGP) phenotypes while showing low risk for virulence and antibiotic resistance. Intact nitrogenase (nif) genes and operons were found in 18 of the isolates. Isolates also encode phosphate solubilization and siderophore production operons, and other PGP genes. The majority of sugarcane isolates showed uniformly low predicted virulence and antibiotic resistance compared to clinical isolates. Six strains with the highest overall genotype scores were experimentally evaluated for nitrogen fixation, phosphate solubilization, and the production of siderophores, gibberellic acid, and indole acetic acid. Results from the biochemical assays were consistent and validated computational phenotype predictions. A genotypic and phenotypic threshold was observed that separated strains by their potential for PGP versus predicted pathogenicity. Our results indicate that computational phenotyping is a promising tool for the assessment of bacteria detected in agricultural ecosystems.

scholarly journals Effect of Abandonment on Diversity and Abundance of Free-Living Nitrogen-Fixing Bacteria and Total Bacteria in the Cropland Soils of Hulun Buir, Inner Mongolia

PLoS ONE ◽  
2014 ◽  
Vol 9 (9) ◽  
pp. e106714 ◽  
Author(s):  
Huhe ◽  
Shinchilelt Borjigin ◽  
Yunxiang Cheng ◽  
Nobukiko Nomura ◽  
Toshiaki Nakajima ◽  
...  
Keyword(s):  
Inner Mongolia ◽  
Nitrogen Fixing ◽  
Nitrogen Fixing Bacteria ◽  
Free Living ◽  
Total Bacteria
Sign in / Sign up

Export Citation Format

Share Document