scholarly journals The Rhizobium-Legume Symbiosis: Co-opting Successful Stress Management

2022 ◽  
Vol 12 ◽  
Author(s):  
Justin P. Hawkins ◽  
Ivan J. Oresnik
Keyword(s):  
Model System ◽  
Low Ph ◽  
Complex Signal ◽  
Tolerance Mechanisms ◽  
Positive Interaction ◽  
Bacterial Response ◽  
Plant Peptides ◽  
Legume Symbiosis ◽  
Growth Inhibiting ◽  
Signal Exchange

The interaction of bacteria with plants can result in either a positive, negative, or neutral association. The rhizobium-legume interaction is a well-studied model system of a process that is considered a positive interaction. This process has evolved to require a complex signal exchange between the host and the symbiont. During this process, rhizobia are subject to several stresses, including low pH, oxidative stress, osmotic stress, as well as growth inhibiting plant peptides. A great deal of work has been carried out to characterize the bacterial response to these stresses. Many of the responses to stress are also observed to have key roles in symbiotic signaling. We propose that stress tolerance responses have been co-opted by the plant and bacterial partners to play a role in the complex signal exchange that occurs between rhizobia and legumes to establish functional symbiosis. This review will cover how rhizobia tolerate stresses, and how aspects of these tolerance mechanisms play a role in signal exchange between rhizobia and legumes.

scholarly journals Rhizobium leguminosarum bv. trifolii NodD2 Enhances Competitive Nodule Colonization in the Clover-Rhizobium Symbiosis

2020 ◽  
Vol 86 (18) ◽  
Author(s):  
Shaun Ferguson ◽  
Anthony S. Major ◽  
John T. Sullivan ◽  
Scott D. Bourke ◽  
Simon J. Kelly ◽  
...  
Keyword(s):  
Competitive Ability ◽  
Rhizobium Leguminosarum ◽  
Complex Signal ◽  
Nodule Formation ◽  
Pasture Production ◽  
Content Type ◽  
Multiple Copies ◽  
Thread Formation ◽  
Legume Symbiosis ◽  
Signal Exchange

ABSTRACT Establishment of the symbiotic relationship that develops between rhizobia and their legume hosts is contingent upon an interkingdom signal exchange. In response to host legume flavonoids, NodD proteins from compatible rhizobia activate expression of nodulation genes that produce lipochitin oligosaccharide signaling molecules known as Nod factors. Root nodule formation commences upon legume recognition of compatible Nod factor. Rhizobium leguminosarum was previously considered to contain one copy of nodD; here, we show that some strains of the Trifolium (clover) microsymbiont R. leguminosarum bv. trifolii contain a second copy designated nodD2. nodD2 genes were present in 8 out of 13 strains of R. leguminosarum bv. trifolii, but were absent from the genomes of 16 R. leguminosarum bv. viciae strains. Analysis of single and double nodD1 and nodD2 mutants in R. leguminosarum bv. trifolii strain TA1 revealed that NodD2 was functional and enhanced nodule colonization competitiveness. However, NodD1 showed significantly greater capacity to induce nod gene expression and infection thread formation. Clover species are either annual or perennial and this phenological distinction is rarely crossed by individual R. leguminosarum bv. trifolii microsymbionts for effective symbiosis. Of 13 strains with genome sequences available, 7 of the 8 effective microsymbionts of perennial hosts contained nodD2, whereas the 3 microsymbionts of annual hosts did not. We hypothesize that NodD2 inducer recognition differs from NodD1, and NodD2 functions to enhance competition and effective symbiosis, which may discriminate in favor of perennial hosts. IMPORTANCE Establishment of the rhizobium-legume symbiosis requires a highly specific and complex signal exchange between both participants. Rhizobia perceive legume flavonoid compounds through LysR-type NodD regulators. Often, rhizobia encode multiple copies of nodD, which is one determinant of host specificity. In some species of rhizobia, the presence of multiple copies of NodD extends their symbiotic host-range. Here, we identified and characterized a second copy of nodD present in some strains of the clover microsymbiont Rhizobium leguminosarum bv. trifolii. The second nodD gene contributed to the competitive ability of the strain on white clover, an important forage legume. A screen for strains containing nodD2 could be utilized as one criterion to select strains with enhanced competitive ability for use as inoculants for pasture production.

scholarly journals Crystal Structure of Bovine Alpha-Chymotrypsin in Space Group P65

Crystals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 460 ◽  
Author(s):  
Andrew Marshall ◽  
Benjamin Keiller ◽  
Jordan Pederick ◽  
Andrew Abell ◽  
John Bruning
Keyword(s):  
Crystal Structure ◽  
Crystal Lattice ◽  
Ammonium Sulphate ◽  
Serine Proteases ◽  
Protein Crystallization ◽  
Model System ◽  
Low Ph ◽  
Unit Cell Parameters ◽  
Space Group ◽  
Cell Parameters

Chymotrypsin is a protease that is commonly used as a standard for protein crystallization and as a model system for studying serine proteases. Unliganded bovine α-chymotrypsin was crystallized at neutral pH using ammonium sulphate as the precipitant, resulting in crystals that conform to P65 symmetry with unit cell parameters that have not been reported previously. Inspection of crystallographic interfaces revealed that the major interface between any two molecules in the crystal lattice represents the interface of the biological dimer, as previously observed for crystals of unliganded α-chymotrypsin grown at low pH in space group P21.

scholarly journals Adaptation of Alphaviruses to Heparan Sulfate: Interaction of Sindbis and Semliki Forest Viruses with Liposomes Containing Lipid-Conjugated Heparin

2002 ◽  
Vol 76 (20) ◽  
pp. 10128-10137 ◽  
Author(s):  
Jolanda M. Smit ◽  
Barry-Lee Waarts ◽  
Koji Kimata ◽  
William B. Klimstra ◽  
Robert Bittman ◽  
...  
Keyword(s):  
Cell Surface ◽  
Heparan Sulfate ◽  
Sindbis Virus ◽  
Semliki Forest Virus ◽  
Model System ◽  
Low Ph ◽  
Wild Type ◽  
Enveloped Viruses ◽  
Neutral Ph ◽  
Receptor Interactions

ABSTRACT Passage of Sindbis virus (SIN) in BHK-21 cells has been shown to select for virus mutants with high affinity for the glycosaminoglycan heparan sulfate (HS). Three loci in the viral spike protein E2 (E2:1, E2:70, and E2:114) have been identified that mutate during adaptation and independently confer on the virus the ability to bind to cell surface HS (W. B. Klimstra, K. D. Ryman, and R. E. Johnston, J. Virol. 72:7357-7366, 1998). In this study, we used HS-adapted SIN mutants to evaluate a new model system involving target liposomes containing lipid-conjugated heparin (HepPE) as an HS receptor analog for the virus. HS-adapted SIN, but not nonadapted wild-type SIN TR339, interacted efficiently with HepPE-containing liposomes at neutral pH. Binding was competitively inhibited by soluble heparin. Despite the efficient binding of HS-adapted SIN to HepPE-containing liposomes at neutral pH, there was no fusion under these conditions. Fusion did occur, however, at low pH, consistent with cellular entry of the virus via acidic endosomes. At low pH, wild-type or HS-adapted SIN underwent fusion with liposomes with or without HepPE with similar kinetics, suggesting that interaction with the HS receptor analog at neutral pH has little influence on subsequent fusion of SIN at low pH. Finally, Semliki Forest virus (SFV), passaged frequently on BHK-21 cells, also interacted efficiently with HepPE-containing liposomes, indicating that SFV, like other alphaviruses, readily adapts to cell surface HS. In conclusion, the liposomal model system presented in this paper may serve as a novel tool for the study of receptor interactions and membrane fusion properties of HS-interacting enveloped viruses.

Bacterial Response to Copper in the Environment: Copper Resistance in Escherichia coli as a Model System

1990 ◽  
pp. 625-632 ◽  
Author(s):  
B. T. O. Lee ◽  
N. L. Brown ◽  
S. Rogers ◽  
A. Bergemann ◽  
J. Camakaris ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Model System ◽  
Copper Resistance ◽  
Bacterial Response

Modification of rhizosphere pH by the symbiotic legume Aspalathus linearis growing in a sandy acidic soil

2000 ◽  
Vol 27 (12) ◽  
pp. 1169 ◽  
Author(s):  
Mmboneni L. Muofhe ◽  
Felix. D. Dakora
Keyword(s):  
Nutrient Solution ◽  
Low Ph ◽  
Rhizosphere Ph ◽  
Rhizosphere Soils ◽  
A Value ◽  
Aspalathus Linearis ◽  
Legume Symbiosis ◽  
Solution Bathing ◽  
Uninoculated Control ◽  
Tea Production

Aspalathus linearis is a N2-fixing legume used for tea production, and grows in highly acidic soils (pH 3–5.3) of the Cederberg mountains in South Africa. Field and glasshouse studies revealed significantly higher pH in rhizosphere than non-rhizosphere soils. However, when six non-legume species were studied in adjacent fields, there were no differences in pH between rhizosphere and non-rhizosphere soils. The culture of A. linearis plants in sterile Leonard jars similarly showed a marked increase of 2.8 pH units in the nutrient solution bathing the roots of inoculated (nodulated) plants, compared to 1.5 pH units in uninoculated control. The uptake and reduction of NO3– by plants fed 2 mM NO3– also raised the rhizosphere pH by 3.5 units, a value comparable to that of the nodulated plants. The use of titrimetric methods showed that OH– and HCO3– were the components of alkalinity in the nutrient solution bathing roots of A. linearis, and were directly responsible for the increase in rhizosphere pH. These findings suggest that the ability to raise rhizosphere pH is an adaptative feature of this legume symbiosis that overcomes the adverse effects of low pH in enhancing nutrient acquisition and reducing trace element toxicity.

scholarly journals Proteome analysis reveals a significant host-specific response in Rhizobium leguminosarum bv viciae endosymbiotic cells

2020 ◽  
pp. mcp.RA120.002276
Author(s):  
David Durán ◽  
Marta Albareda ◽  
Anabel Marina ◽  
Carlos García ◽  
Tomas Ruiz-Argüeso ◽  
...  
Keyword(s):  
Rhizobium Leguminosarum ◽  
Tricarboxylic Acid Cycle ◽  
Proteome Analysis ◽  
Specific Response ◽  
Carbon And Nitrogen ◽  
Bacterial Proteins ◽  
Bacterial Response ◽  
Carbon Compounds ◽  
Legume Symbiosis ◽  
Related Proteins

The Rhizobium-legume symbiosis is a beneficial interaction in which the bacterium converts atmospheric nitrogen into ammonia and delivers it to the plant in exchange for carbon compounds. This symbiosis implies the adaptation of bacteria to live inside host plant cells. In this work we apply RP-LC-MS/MS and  iTRAQ techniques to study the proteomic profile of endosymbiotic cells (bacteroids) induced by Rhizobium leguminosarum bv viciae strain UPM791 in legume nodules. Nitrogenase subunits, tricarboxylic acid cycle enzymes, and stress response proteins are amongst the most abundant from over one thousand rhizobial proteins identified in pea (Pisum sativum) bacteroids. Comparative analysis of bacteroids induced in pea and in lentil (Lens culinaris)nodules revealed the existence of a significant host-specific differential response affecting dozens of bacterial proteins, including stress-related proteins, transcriptional regulators, and proteins involved in the carbon and nitrogen metabolisms. A mutant affected in one of these proteins, homologous to a GntR-like transcriptional regulator, showed a symbiotic performance significantly  impaired in symbiosis with pea, but not with lentil plants. Analysis of the proteomes of bacteroids isolated from both hosts also revealed the presence of different sets of plant-derived nodule-specific cysteine rich (NCR) peptides, indicating that the endosymbiotic bacteria find a host-specific cocktail of chemical stressors inside the nodule. By studying variations of the bacterial response to different plant cell environments we will be able to identify specific limitations imposed by the host that might give us clues for the improvement of rhizobial performance.

scholarly journals Microphotometric analysis of protein-bound thiols and disulfides with an azogenic maleimide.

1981 ◽  
Vol 29 (7) ◽  
pp. 817-821 ◽  
Author(s):  
D A Wiese ◽  
T O Sippel
Keyword(s):  
Disulfide Bonds ◽  
Thiol Group ◽  
Model System ◽  
Low Ph ◽  
Chemical Analyses ◽  
Absolute Quantitation ◽  
Biological Objects ◽  
Before And After ◽  
Thiol Reagent

The chromogenic thiol reagent N-(4-aminophenyl)-maleimide (APM) was used to provide a sensitive procedure for the determination of protein-bound thiol group, both before and after reduction of disulfide bonds by tri-n-butylphosphine. The bound reagent is diazotized and coupled at low pH to N-(1-naphthyl)ethylenediamine to form an intense magenta label (lambda max 547 nm) with a high molar absorbancy (epsilon 547 = 49,800 cm2/mmol). The validity of absolute quantitation afforded by the method was shown by comparing the results with standard chemical analyses of thiol contents in a model system. Furthermore, the applicability of the procedure to biological objects was shown on isolated epididymal bull sperm heads.

Molecular biology of signal exchange in the Rhizobium/Sinorhizobium/Mesorhizobium legume symbiosis

2001 ◽  
pp. 618-619
Author(s):  
D. Werner ◽  
H. Steele ◽  
C. Bolaños-Vasquez ◽  
P. Vinuesa
Keyword(s):  
Molecular Biology ◽  
Legume Symbiosis ◽  
Signal Exchange
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