scholarly journals Carbamoylation of Azorhizobial Nod Factors Is Mediated by NodU

1999 ◽  
Vol 12 (1) ◽  
pp. 68-73 ◽  
Author(s):  
Wim D'Haeze ◽  
Marc Van Montagu ◽  
Jean-Claude Promé ◽  
Marcelle Holsters
Keyword(s):  
Escherichia Coli ◽  
Structural Analysis ◽  
Nod Factors ◽  
Azorhizobium Caulinodans ◽  
Terminal Residue ◽  
Azorhizobium Caulinodans Ors571 ◽  
Sequence Similarities ◽  
Carbamoyl Group

Lipochitooligosaccharides (LCOs) synthesized by Azorhizobium caulinodans ORS571 are substituted at the nonreducing-terminal residue with a 6-O-carbamoyl group. LCO biosynthesis in A. caulinodans is dependent on the nodABCSUIJZnoeC operon. Until now, the role of the nodulation protein NodU in the synthesis of azorhizobial LCOs remained unclear. Based on sequence similarities and structural analysis of LCOs produced by a nodU mutant, a complemented nodU mutant, and Escherichia coli DH5α expressing the nodABCSU genes, NodU was shown to be involved in the carbamoylation step.

Role of nodl and nodj in lipo-chitooligosaccharide secretion in Azorhizobium caulinodans and Escherichia coli

1996 ◽  
Vol 20 (5) ◽  
pp. 993-1000 ◽  
Author(s):  
Manuel Fernández-López ◽  
Wim D'Haeze ◽  
Peter Mergaert ◽  
Christa Verplancke ◽  
Jean-Claude Prome ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Azorhizobium Caulinodans

scholarly journals A Dual Role of Amino Acids from Sesbania rostrata Seed Exudates in the Chemotaxis Response of Azorhizobium caulinodans ORS571

2019 ◽  
Vol 32 (9) ◽  
pp. 1134-1147 ◽  
Author(s):  
Xiaolin Liu ◽  
Zhihong Xie ◽  
Yixuan Wang ◽  
Yu Sun ◽  
Xiaoxiao Dang ◽  
...  
Keyword(s):  
Amino Acids ◽  
Dual Role ◽  
Chemotactic Response ◽  
Nodule Formation ◽  
Sesbania Rostrata ◽  
Azorhizobium Caulinodans ◽  
Regulation Of Expression ◽  
Chemotaxis Proteins ◽  
Azorhizobium Caulinodans Ors571

Azorhizobium caulinodans ORS571 can induce nodule formation on the roots and the stems of its host legume, Sesbania rostrata. Plant exudates are essential in the dialogue between microbes and their host plant and, in particular, amino acids can play an important role in the chemotactic response of bacteria. Histidine, arginine, and aspartate, which are the three most abundant amino acids present in S. rostrata seed exudates, behave as chemoattractants toward A. caulinodans. A position-specific-iterated BLAST analysis of the methyl-accepting chemotaxis proteins (MCPs) (chemoreceptors) in the genome of A. caulinodans was performed. Among the 43 MCP homologs, two MCPs harboring a dCache domain were selected as possible cognate amino acid MCPs. After analysis of relative gene expression levels and construction of a gene-deleted mutant strain, one of them, AZC_0821 designed as TlpH, was confirmed to be responsible for the chemotactic response to the three amino acids. In addition, it was found that these three amino acids can also influence chemotaxis of A. caulinodans independently of the chemosensory receptors, by being involved in the increase of the expression level of several che and fla genes involved in the chemotaxis pathway and flagella synthesis. Thus, the contribution of amino acids present in seed exudates is directly related to the role as chemoattractants and indirectly related to the role in the regulation of expression of key genes involved in chemotaxis and motility. This “dual role” is likely to influence the formation of biofilms by A. caulinodans and the host root colonization properties of this bacterium.

Identification of biochemical and putative biological role of a xenolog from Escherichia coli using structural analysis

2011 ◽  
Vol 79 (4) ◽  
pp. 1132-1142 ◽  
Author(s):  
Varun Bhaskar ◽  
Manoj Kumar ◽  
Sankar Manicka ◽  
Sunil Tripathi ◽  
Aparna Venkatraman ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Structural Analysis ◽  
Biological Role

Root nodulation of Sesbania rostrata suppresses stem nodulation by Sinorhizobium teranga but not Azorhizobium caulinodans

1996 ◽  
Vol 42 (2) ◽  
pp. 187-190 ◽  
Author(s):  
Kodjo Tomekpe ◽  
Marcelle Holsters ◽  
Bernard Dreyfus
Keyword(s):  
Host Plant ◽  
Root Nodules ◽  
Sesbania Rostrata ◽  
Efficient Production ◽  
Nod Factors ◽  
Azorhizobium Caulinodans ◽  
Experimental Conditions ◽  
Nod Factor ◽  
Stem Nodulation ◽  
Azorhizobium Caulinodans Ors571

Azorhizobium caulinodans ORS571 and Sinorhizobium teranga ORS51 and ORS52 are symbionts of the same host plant Sesbania rostrata. In nature, A. caulinodans nodulates more competitively the stem-located infection sites of Sesbania rostrata. Sinorhizobium strains, although frequently present in root nodules, are seldom found in stem nodules. One probable explanation for this phenomenon is the more abundant presence of Azorhizobium on the leaf and stem surfaces of the host plant. Work presented here hints at other plausible factors that determine the greater "stem specificity" of Azorhizobium. We found that under experimental conditions in which roots are not inoculated, all strains nodulated stems very well. However, ORS51 and ORS52 were much more sensitive than ORS571 to suppression of stem nodulation by previous root inoculation. The introduction of the regulatory nodD gene from A. caulinodans diminished the sensitivity to this suppression, probably by enhanced nod gene expression and subsequent Nod factor production. Our hypothesis is that the greater infectivity of ORS571 is due to a more efficient production of mitogenic Nod factors at stem-located infection sites, thereby more readily overcoming systemic suppression caused by previous root inoculations.Key words: autoregulation, nitrogen fixation, rhizobial ecology, systemic suppression of nodulation.

scholarly journals noeM, a New Nodulation Gene Involved in the Biosynthesis of Nod Factors with an Open-Chain Oxidized Terminal Residue and in the Symbiosis with Mimosa pudica

2019 ◽  
Vol 32 (12) ◽  
pp. 1635-1648 ◽  
Author(s):  
Benoit Daubech ◽  
Verena Poinsot ◽  
Agnieszka Klonowska ◽  
Delphine Capela ◽  
Clémence Chaintreuil ◽  
...  
Keyword(s):  
Transmembrane Protein ◽  
Fatty Acyl ◽  
Mimosa Pudica ◽  
Nod Factors ◽  
Open Chain ◽  
Nod Factor ◽  
Terminal Residue ◽  
Fatty Acid Hydroxylase ◽  
Acyl Chains

The β-rhizobium Cupriavidus taiwanensis is a nitrogen-fixing symbiont of Mimosa pudica. Nod factors produced by this species were previously found to be pentameric chitin-oligomers carrying common C18:1 or C16:0 fatty acyl chains, N-methylated and C-6 carbamoylated on the nonreducing terminal N-acetylglucosamine and sulfated on the reducing terminal residue. Here, we report that, in addition, C. taiwanensis LMG19424 produces molecules where the reducing sugar is open and oxidized. We identified a novel nodulation gene located on the symbiotic plasmid pRalta, called noeM, which is involved in this atypical Nod factor structure. noeM encodes a transmembrane protein bearing a fatty acid hydroxylase domain. This gene is expressed during symbiosis with M. pudica and requires NodD and luteolin for optimal expression. The closest noeM homologs formed a separate phylogenetic clade containing rhizobial genes only, which are located on symbiosis plasmids downstream from a nod box. Corresponding proteins, referred to as NoeM, may have specialized in symbiosis via the connection to the nodulation pathway and the spread in rhizobia. noeM was mostly found in isolates of the Mimoseae tribe, and specifically detected in all tested strains able to nodulate M. pudica. A noeM deletion mutant of C. taiwanensis was affected for the nodulation of M. pudica, confirming the role of noeM in the symbiosis with this legume.

scholarly journals Specific Flavonoids Promote Intercellular Root Colonization of Arabidopsis thaliana by Azorhizobium caulinodans ORS571

1997 ◽  
Vol 10 (5) ◽  
pp. 560-570 ◽  
Author(s):  
Clare Gough ◽  
Christine Galera ◽  
Jacques Vasse ◽  
Gordon Webster ◽  
Edward C. Cocking ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Root Colonization ◽  
Lateral Roots ◽  
Nod Factors ◽  
Azorhizobium Caulinodans ◽  
Nutritional Factors ◽  
High Frequencies ◽  
Cell Layers ◽  
Azorhizobium Caulinodans Ors571 ◽  
Stimulation Of

The ability of Azorhizobium caulinodans ORS571 and other diazotrophic bacteria to internally colonize roots of Arabidopsis thaliana has been studied. Strains tagged with lacZ or gusA reporter genes were used, and the principal colonization sites were found to be the points of emergence of lateral roots, lateral root cracks (LRCs). High frequencies of colonization were found; 63 to 100% of plants were colonized by ORS571, and 100% of plants were colonized by Herbaspirillum seropedicae. After LRCs were colonized, bacteria moved into intercellular spaces between the cortical and endodermal cell layers. Specific flavonoids, naringenin and daidzein, at 5 × 10-5 M, significantly promoted colonization by ORS571. By using a nodC and a nodD mutant of ORS571, it was shown that neither Nod factors nor NodD are involved in colonization or flavonoid stimulation of colonization. Flavonoids did not appear to be stimulating LRC colonization by their activity as nutritional factors. LRC and intercellular colonization by H. seropedicae was stimulated by naringenin and daidzein at the same concentration that stimulated colonization by ORS571.

scholarly journals A Chemotaxis-Like Pathway of Azorhizobium caulinodans Controls Flagella-Driven Motility, Which Regulates Biofilm Formation, Exopolysaccharide Biosynthesis, and Competitive Nodulation

2018 ◽  
Vol 31 (7) ◽  
pp. 737-749 ◽  
Author(s):  
Wei Liu ◽  
Yu Sun ◽  
Rimin Shen ◽  
Xiaoxiao Dang ◽  
Xiaolin Liu ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Biofilm Formation ◽  
Competitive Adsorption ◽  
Root Surface ◽  
Extracellular Polysaccharides ◽  
Azorhizobium Caulinodans ◽  
Mutant Strains ◽  
Exopolysaccharide Biosynthesis ◽  
Azorhizobium Caulinodans Ors571

The genome of the Azorhizobium caulinodans ORS571 contains a unique chemotaxis gene cluster (che) including five chemotaxis genes: cheA, cheW, cheY1, cheB, and cheR. Analysis of the role of the chemotaxis cluster of A. caulinodans using deletion mutant strains revealed that CheA or the Che signaling pathway controls chemotaxis behavior and flagella-driven motility and plays important roles in formation of biofilms and production of extracellular polysaccharides (EPS). Furthermore, the deletion mutants (ΔcheA and ΔcheA-R) were defective in competitive adsorption and colonization on the root surface of host plants. In addition, a functional CheA or Che pathway promoted competitive nodulation on roots and stems. Interestingly, a nonflagellated mutant, ΔfliM, displayed a phenotype highly similar to that of the ΔcheA or ΔcheA-R mutant strains. These findings suggest that through controlling flagella-driven motility behavior, the chemotaxis signaling pathway in A. caulinodans coordinates biofilm formation, EPS, and competitive colonization and nodulation.

scholarly journals S-Methylmethionine Metabolism in Escherichia coli

1999 ◽  
Vol 181 (2) ◽  
pp. 662-665 ◽  
Author(s):  
Martin Thanbichler ◽  
Bernhard Neuhierl ◽  
August Böck
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Sequence Similarity ◽  
Physiological Role ◽  
High Sequence Similarity ◽  
Reading Frame ◽  
Amino Acid Permeases ◽  
Sequence Similarities ◽  
Homocysteine Methyltransferase

ABSTRACT Selenium-accumulating Astragalus spp. contain an enzyme which specifically transfers a methyl group fromS-methylmethionine to the selenol of selenocysteine, thus converting it to a nontoxic, since nonproteinogenic, amino acid. Analysis of the amino acid sequence of this enzyme revealed thatEscherichia coli possesses a protein (YagD) which shares high sequence similarity with the enzyme. The properties and physiological role of YagD were investigated. YagD is anS-methylmethionine: homocysteine methyltransferase which also accepts selenohomocysteine as a substrate. Mutants inyagD which also possess defects in metE andmetH are unable to utilize S-methylmethionine for growth, whereas a metE metH double mutant still grows on S-methylmethionine. Upstream of yagD and overlapping with its reading frame is a gene (ykfD) which, when inactivated, also blocks growth on methylmethionine in ametE metH genetic background. Since it displays sequence similarities with amino acid permeases it appears to be the transporter for S-methylmethionine. Methionine but notS-methylmethionine in the medium reduces the amount ofyagD protein. This and the existence of four MET box motifs upstream of yfkD indicate that the two genes are members of the methionine regulon. The physiological roles of the ykfDand yagD products appear to reside in the acquisition ofS-methylmethionine, which is an abundant plant product, and its utilization for methionine biosynthesis.

The role of Constitutional Courts in Transitional Justice: Colombia and South Africa

2016 ◽  
Vol 9 (15) ◽  
Author(s):  
Nadiehezka Paola Palencia Tejedor
Keyword(s):  
South Africa ◽  
Structural Analysis ◽  
Transitional Justice ◽  
Critical Analysis ◽  
Historical Context ◽  
Constitutional Courts ◽  
Political Background ◽  
Similarities And Differences ◽  
Peace And Reconciliation

This work focuses on a compared analysis of the South Afri- can decision related to the “peace and reconciliation act” of this country’s Parliament, and the Colombian decision regarding the amendment of the constitution called “The juridical framework for the peace.” Turning to the structure, it is developed in three major topics: 1. It provides a brief of the historical context, political background and an overview of the two decisions.2. It gives a structural analysis of the powers that each Court has and the nature of the constitutional mechanism through which both Courts decided the constitutionality of the said norms 3. It presents a critical analysis on the similarities and differences between the two systems and judgments. It presents some con- clusions. 

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