Structure, functions and perspectives of practical application of the signal molecules inducing development of rhizobia-legume symbiosis

Soil bacteria rhizobia establish nitrogen-fixing symbiosis with legume plants. Mutual recognition of symbiotic partners and initiation of nodule formation occur via exchange by molecular signals secreted both by plant and bacteria. This review summarizes recent data about structural diversity, genetic control of biosynthesis and functional role of Nod-factors. The possibilities of practical application of flavonoids and Nod-factors in agriculture are discussed

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Rhizobial NodL O-Acetyl Transferase and NodS N-Methyl Transferase Functionally Interfere in Production of Modified Nod Factors

Journal of Bacteriology ◽

10.1128/jb.183.11.3408-3416.2001 ◽

2001 ◽

Vol 183 (11) ◽

pp. 3408-3416 ◽

Cited By ~ 10

Author(s):

Isabel M. López-Lara ◽

Dimitris Kafetzopoulos ◽

Herman P. Spaink ◽

Jane E. Thomas-Oates

Keyword(s):

Nodule Formation ◽

Signal Molecules ◽

Nod Factors ◽

Rhizobium Tropici ◽

Methyl Transferase ◽

Mesorhizobium Loti ◽

Methyl Group ◽

Rhizobial Species ◽

Acetyl Group

ABSTRACT The products of the rhizobial nodulation genes are involved in the biosynthesis of lipochitin oligosaccharides (LCOs), which are host-specific signal molecules required for nodule formation. The presence of an O-acetyl group on C-6 of the nonreducingN-acetylglucosamine residue of LCOs is due to the enzymatic activity of NodL. Here we show that transfer of the nodLgene into four rhizobial species that all normally produce LCOs that are not modified on C-6 of the nonreducing terminal residue results in production of LCOs, the majority of which have an acetyl residue substituted on C-6. Surprisingly, in transconjugant strains ofMesorhizobium loti, Rhizobium etli, and Rhizobium tropici carrying nodL, such acetylation of LCOs prevents the endogenous nodS-dependent transfer of theN-methyl group that is found as a substituent of the acylated nitrogen atom. To study this interference betweennodL and nodS, we have cloned thenodS gene of M. loti and used its product in in vitro experiments in combination with purified NodL protein. It has previously been shown that a chitooligosaccharide N deacetylated on the nonreducing terminus (the so-called NodBC metabolite) is the preferred substrate for NodS as well as for NodL. Here we show that the NodBC metabolite, acetylated by NodL, is not used by the NodS protein as a substrate while the NodL protein can acetylate the NodBC metabolite that has been methylated by NodS.

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ROLE OF SIGNAL EXCHANGE IN CONTROL OF RHIZOBIUM - LEGUME SYMBIOSIS SPECIFICITY

Ecological genetics ◽

10.17816/ecogen6227-34 ◽

2008 ◽

Vol 6 (2) ◽

pp. 27-34

Author(s):

Elena A Dolgikh ◽

Irina V Leppyanen ◽

Maria A Osipova ◽

Igor A Tikhonovich

Keyword(s):

Molecular Mechanisms ◽

Root Nodules ◽

Signal Transduction Pathway ◽

Basic Research ◽

Future Application ◽

Signal Molecules ◽

Nod Factors ◽

Legume Symbiosis ◽

Legume Plants ◽

Chemical Groups

The signal molecules produced by legume plants and soil bacteria rhizobia and involved in early steps of symbiosis regulation were identified through the evaluation of molecular mechanisms of plant-rhizobia communication. The molecular dialog between plants and rhizobia is initiated by plant flavanoids inducing the synthesis and secretion of lipochitooligosaccharide molecules Nod factors by rhizobial bacteria. Nod factors are N-acetylglucosamine oligomers, modified by fatty acid and certain chemical groups. Nod factors trigger a set of plant reactions resulting in a formation of root nodules - nitrogen fixing symbiotic organs. Fine chemical structure of signal molecules determines host specificity of the symbiosis. Nod factors are active in low concentrations and possess mitogenic and morphogenic activity, therefore they are recognized as the new class of growth regulators. In this paper the modern data about study of Nod factor perception mechanisms and signal transduction pathway in legume plants are presented and considered with perspective for future application of these knowledge for practical increasing of symbiosis efficiency from plant side. This work was supported by RFBR 07-08-00700a (Russian Foundation of Basic Research), CRDF RUXO-012-ST-06 (BP2M12) and HIII-5399. 2008. 4, RFBR-NWO (06-04-89000-НВОЦ-а) grants.

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Roles of flavonoids and the transcriptional regulator TtsI in the activation of the type III secretion system of Bradyrhizobium elkanii SEMIA587

Microbiology ◽

10.1099/mic.0.040873-0 ◽

2011 ◽

Vol 157 (3) ◽

pp. 627-635 ◽

Cited By ~ 7

Author(s):

Samanta Bolzan de Campos ◽

William J. Deakin ◽

William J. Broughton ◽

Luciane M. P. Passaglia

Keyword(s):

Type Iii Secretion ◽

Nodule Formation ◽

Secretion Systems ◽

Promoter Regions ◽

Type Iii ◽

Conserved Sequence ◽

Type Iii Secretion Systems ◽

Bradyrhizobium Elkanii ◽

Molecular Signals

Bradyrhizobium elkanii SEMIA587 is a symbiotic nitrogen-fixing bacterium of the group commonly called rhizobia, which induce nodule formation in legumes, and is widely used in Brazilian commercial inoculants of soybean. In response to flavonoid compounds released by plant roots, besides Nod factors, other molecular signals are secreted by rhizobia, such as proteins secreted by type III secretion systems (T3SSs). Rhizobial T3SSs are activated by the transcription regulator TtsI, which binds to sequences present in the promoter regions of T3SS genes via a conserved sequence called the tts box. To study the role of the T3SS of B. elkanii SEMIA587, ttsI was mutated. Protein secretion and flavonoid induction analysis, as well as nodulation tests, were performed with the wild-type and mutant strains. The results obtained showed that B. elkanii SEMIA587 secretes at least two proteins (NopA and NopL, known rhizobial T3SS substrates) after genistein induction, whilst supernatants of the ttsI mutant did not contain these Nops. Unusually for rhizobia, the promoter region of the B. elkanii SEMIA587 ttsI gene contains a tts box, which is responsive to flavonoid induction and to which TtsI can bind. Nodulation tests performed with three different leguminous plants showed that the B. elkanii SEMIA587 ttsI mutant displays host-dependent characteristics; in particular, nodulation of two soybean cultivars, Peking and EMBRAPA 48, was more efficient when TtsI of B. elkanii was functional.

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Nod genes and Nod signals and the evolution of the Rhizobium legume symbiosis.

Acta Biochimica Polonica ◽

10.18388/abp.2001_3921 ◽

2001 ◽

Vol 48 (2) ◽

pp. 359-365 ◽

Cited By ~ 33

Author(s):

F Debellé ◽

L Moulin ◽

B Mangin ◽

J Dénarié ◽

C Boivin

Keyword(s):

Fatty Acids ◽

Unsaturated Fatty Acids ◽

Acyl Chain ◽

Nod Factors ◽

Nod Genes ◽

Low Concentrations ◽

Rhizobial Species ◽

Legume Symbiosis ◽

Alpha Beta

The establishment of the nitrogen-fixing symbiosis between rhizobia and legumes requires an exchange of signals between the two partners. In response to flavonoids excreted by the host plant, rhizobia synthesize Nod factors (NFs) which elicit, at very low concentrations and in a specific manner, various symbiotic responses on the roots of the legume hosts. NFs from several rhizobial species have been characterized. They all are lipo-chitooligosaccharides, consisting of a backbone of generally four or five glucosamine residues N-acylated at the non-reducing end, and carrying various O-substituents. The N-acyl chain and the other substituents are important determinants of the rhizobial host specificity. A number of nodulation genes which specify the synthesis of NFs have been identified. All rhizobia, in spite of their diversity, possess conserved nodABC genes responsible for the synthesis of the N-acylated oligosaccharide core of NFs, which suggests that these genes are of a monophyletic origin. Other genes, the host specific nod genes, specify the substitutions of NFs. The central role of NFs and nod genes in the Rhizobium-legume symbiosis suggests that these factors could be used as molecular markers to study the evolution of this symbiosis. We have studied a number of NFs which are N-acylated by alpha,beta-unsaturated fatty acids. We found that the ability to synthesize such NFs does not correlate with taxonomic position of the rhizobia. However, all rhizobia that produce NFs such nodulate plants belonging to related tribes of legumes, the Trifolieae, Vicieae, and Galegeae, all of them being members of the so-called galegoid group. This suggests that the ability to recognize the NFs with alpha-beta-unsaturated fatty acids is limited to this group of legumes, and thus might have appeared only once in the course of legume evolution, in the galegoid phylum.

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The Role of Peptides in the Design of Electrochemical Biosensors for Clinical Diagnostics

Biosensors ◽

10.3390/bios11080246 ◽

2021 ◽

Vol 11 (8) ◽

pp. 246

Author(s):

Patrick Severin Sfragano ◽

Giulia Moro ◽

Federico Polo ◽

Ilaria Palchetti

Keyword(s):

Functional Groups ◽

Synthetic Peptides ◽

Clinical Diagnostics ◽

Electrochemical Biosensors ◽

Practical Application ◽

Design And Development ◽

Electrode Surfaces ◽

Electrochemical Transducers ◽

Target Analyte

Peptides represent a promising class of biorecognition elements that can be coupled to electrochemical transducers. The benefits lie mainly in their stability and selectivity toward a target analyte. Furthermore, they can be synthesized rather easily and modified with specific functional groups, thus making them suitable for the development of novel architectures for biosensing platforms, as well as alternative labelling tools. Peptides have also been proposed as antibiofouling agents. Indeed, biofouling caused by the accumulation of biomolecules on electrode surfaces is one of the major issues and challenges to be addressed in the practical application of electrochemical biosensors. In this review, we summarise trends from the last three years in the design and development of electrochemical biosensors using synthetic peptides. The different roles of peptides in the design of electrochemical biosensors are described. The main procedures of selection and synthesis are discussed. Selected applications in clinical diagnostics are also described.

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Systems Biology and Bile Acid Signalling in Microbiome-Host Interactions in the Cystic Fibrosis Lung

Antibiotics ◽

10.3390/antibiotics10070766 ◽

2021 ◽

Vol 10 (7) ◽

pp. 766

Author(s):

David F. Woods ◽

Stephanie Flynn ◽

Jose A. Caparrós-Martín ◽

Stephen M. Stick ◽

F. Jerry Reen ◽

...

Keyword(s):

Cystic Fibrosis ◽

Bile Acids ◽

Host Response ◽

Signal Molecules ◽

Therapeutic Approaches ◽

Related Factors ◽

Host Interactions ◽

Important Host ◽

Respiratory Microbiota

The study of the respiratory microbiota has revealed that the lungs of healthy and diseased individuals harbour distinct microbial communities. Imbalances in these communities can contribute to the pathogenesis of lung disease. How these imbalances occur and establish is largely unknown. This review is focused on the genetically inherited condition of Cystic Fibrosis (CF). Understanding the microbial and host-related factors that govern the establishment of chronic CF lung inflammation and pathogen colonisation is essential. Specifically, dissecting the interplay in the inflammation–pathogen–host axis. Bile acids are important host derived and microbially modified signal molecules that have been detected in CF lungs. These bile acids are associated with inflammation and restructuring of the lung microbiota linked to chronicity. This community remodelling involves a switch in the lung microbiota from a high biodiversity/low pathogen state to a low biodiversity/pathogen-dominated state. Bile acids are particularly associated with the dominance of Proteobacterial pathogens. The ability of bile acids to impact directly on both the lung microbiota and the host response offers a unifying principle underpinning the pathogenesis of CF. The modulating role of bile acids in lung microbiota dysbiosis and inflammation could offer new potential targets for designing innovative therapeutic approaches for respiratory disease.

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Glycans in autophagy, endocytosis and lysosomal functions

Glycoconjugate Journal ◽

10.1007/s10719-021-10007-x ◽

2021 ◽

Author(s):

Fulvio Reggiori ◽

Hans-Joachim Gabius ◽

Massimo Aureli ◽

Winfried Römer ◽

Sandro Sonnino ◽

...

Keyword(s):

Sugar Code ◽

Endogenous Lectins ◽

Biological Aspects ◽

Molecular Signals ◽

Lysosomal Proteins ◽

In Cells

AbstractGlycans have been shown to function as versatile molecular signals in cells. This prompted us to look at their roles in endocytosis, endolysosomal system and autophagy. We start by introducing the cell biological aspects of these pathways, the concept of the sugar code, and provide an overview on the role of glycans in the targeting of lysosomal proteins and in lysosomal functions. Moreover, we review evidence on the regulation of endocytosis and autophagy by glycans. Finally, we discuss the emerging concept that cytosolic exposure of luminal glycans, and their detection by endogenous lectins, provides a mechanism for the surveillance of the integrity of the endolysosomal compartments, and serves their eventual repair or disposal.

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Isovitexin modulates autophagy in Alzheimer’s disease via miR-107 signalling

Translational Neuroscience ◽

10.1515/tnsci-2020-0109 ◽

2020 ◽

Vol 11 (1) ◽

pp. 391-401

Author(s):

Jiang Cheng ◽

Guowei Wang ◽

Na Zhang ◽

Fang Li ◽

Lina Shi ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Memory Loss ◽

The Elderly ◽

Tnf Α ◽

Autophagic Process ◽

Molecular Signals ◽

Ad Mouse Model ◽

Mtor Signalling

AbstractBackground:Alzheimer’s disease (AD) is an ultimately fatal, degenerative brain disease in the elderly people. In the current work, we assessed the defensive capability of isovitexin (IVX) through an intracerebroventricular injection of streptozotocin (STZ)-induced AD mouse model.Methods:Mice were separated into four cohorts: sham-operated control mice; STZ-intoxicated Alzheimer’s mice; IVX cohort, IVX + STZ; and Ant-107 cohort, antagomiR-107 + IVX/STZ as in the IVX cohort.Results:The outcomes indicated that IVX administration ameliorated spatial memory loss and blunted a cascade of neuro-noxious episodes – including increased amyloid-beta (Aβ) and degraded myelin basic protein burden, neuroinflammation (represented by elevated caspase-1, TNF-α and IL-6 levels) and autophagic dysfunction (represented by altered LC3-II, Atg7 and beclin-1 expressions) – via the inhibition of PI3K/Akt/mTOR signalling axis. We considered the question of whether the epigenetic role of microRNA-107 (miR-107) has any impact on these events, by using antagomiR-107.Conclusion:This probing underscored that miR-107 could be a pivotal regulatory button in the activation of molecular signals linked with the beneficial autophagic process and anti-inflammatory activities in relation to IVX treatment. Hence, this report exemplifies that IVX could guard against Aβ toxicity and serve as an effectual treatment for patients afflicted with AD.

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