Erythritol feeds the pentose phosphate pathway via three new isomerases leading to D-erythrose-4-phosphate in Brucella

Olivares

Chem. Biol. Technol. Agric.

2019

Background: The negative consequences of industrial agriculture greatly affect human health and the environment. Debating our dietary requirements and challenging the means of food production are necessary. In the first years of transitioning to agroecological production, crop yields normally decrease. Humic acids and beneficial bacteria used as plant growth promoters can be helpful during this stressful time. Metabolite target identification will aid in increasing plant responses to these agents. Materials: We evaluated the metabolite fingerprints of maize and sugarcane seedlings after 5 days of treatment with like-humic acids isolated from vermicompost coupled with a combined Herbaspirillum seropedicae and Gluconacetobacter diazotrophicus application. The hydromethanolic foliar extracts were submitted for 1 H nuclear magnetic resonance analysis, and the data were explored using chemometrics procedures. After the preliminary screening, the extracts were analyzed by gas chromatography coupled to time of flight mass spectrometry to identify metabolite targets. Results: The biostimulant significantly changed the metabolic fingerprints independent of the plant species. The main proton spectral regions changed by biostimulant use were from 0 to 2.5 ppm and 3.5 to 5 ppm, as revealed by a principal component analysis. The main signals corresponded to amino acid, sugar and organic acid chemical shifts. Aspartic acid was the amino acid present in greatest amounts in both leaf extracts. A significant change occurred in the region normally attributed to (CH n)-protons bound to electron-withdrawing groups, such as carboxyls from mucic, ribonic and saccharic acids derived from sugars and aromatic structures from shikimic acid, 4-hydroxybenzoate and 3,4-dihydroxycinnamic acid. The main organic acids altered by the biostimulant were representatives of the tricarboxylic acid cycle (citric, isocitric, aconitic, malic and fumaric acids). Linoleic and myristic acids, 1-mono palmitin and tocopherol were the major lipid components found at greater levels in the treated leaf extracts. Compounds from the oxidative end products of ascorbic acid metabolism, like threonic, isothreonic and oxalic acids, are putative biomarkers of the biostimulant as are the cyclic polyol identified as quinic acid and trehalose, a disaccharide involved in plant stress responses. Conclusion: The biostimulant induced significant changes in the metabolite fingerprints of maize and sugarcane seedlings as revealed by nuclear magnetic resonance. Both primary and secondary metabolisms were affected, and 22 putative biomarkers associated with the biostimulant-treated plant phenotype were identified. This agrees with previous work indicating that the stimulation of primary and secondary metabolisms was partially responsible for

Section: Maizementioning

confidence: 70%

Metabolite fingerprints of maize and sugarcane seedlings: searching for markers after inoculation with plant growth-promoting bacteria in humic acids

Olivares

Chem. Biol. Technol. Agric.

2019

“…Construction of the in-frame deletion in eryA was done following a previously described strategy (Barbier et al, 2014). Briefly, approximately 750 bp upstream and downstream of BAB2_0372 were amplified by PCR from genomic DNA of B. abortus 2308.…”

Section: Methodsmentioning

confidence: 99%

Erythritol Availability in Bovine, Murine and Human Models Highlights a Potential Role for the Host Aldose Reductase during Brucella Infection

et al. 2017

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Erythritol is the preferential carbon source for most brucellae, a group of facultative intracellular bacteria that cause a worldwide zoonosis. Since this polyol is abundant in genital organs of ruminants and swine, it is widely accepted that erythritol accounts at least in part for the characteristic genital tropism of brucellae. Nevertheless, proof of erythritol availability and essentiality during Brucella intracellular multiplication has remained elusive. To investigate this relationship, we compared ΔeryH (erythritol-sensitive and thus predicted to be attenuated if erythritol is present), ΔeryA (erythritol-tolerant but showing reduced growth if erythritol is a crucial nutrient) and wild type B. abortus in various infection models. This reporting system indicated that erythritol was available but not required for B. abortus multiplication in bovine trophoblasts. However, mice and humans have been considered to lack erythritol, and we found that it was available but not required for B. abortus multiplication in human and murine trophoblastic and macrophage-like cells, and in mouse spleen and conceptus (fetus, placenta and envelopes). Using this animal model, we found that B. abortus infected cells and tissues contained aldose reductase, an enzyme that can account for the production of erythritol from pentose cycle precursors.

“…These measurements captured known metabolic traits of B. abortus (70), including utilization of erythritol, which has previously been described for Brucella (71,72) and related Rhizobiales (73)(74)(75). B. abortus exhibited growth on several hexose (D-fructose, D-glucose, D-galactose, and D-fucose) and pentose (L-arabinose, D-xylose, D-ribose, and adonitol) sugars, amino acids, and dipeptides.…”

Section: Resultsmentioning

confidence: 93%

WrpA Is an Atypical Flavodoxin Family Protein under Regulatory Control of the Brucella abortus General Stress Response System

et al. 2016

The general stress response (GSR) system of the intracellular pathogen Brucella abortus controls the transcription of approximately 100 genes in response to a range of stress cues. The core genetic regulatory components of the GSR are required for B. abortus survival under nonoptimal growth conditions in vitro and for maintenance of chronic infection in an in vivo mouse model. The functions of the majority of the genes in the GSR transcriptional regulon remain undefined. bab1_1070 is among the most highly regulated genes in this regulon: its transcription is activated 20-to 30-fold by the GSR system under oxidative conditions in vitro. We have solved crystal structures of Bab1_1070 and demonstrate that it forms a homotetrameric complex that resembles those of WrbA-type NADH:quinone oxidoreductases, which are members of the flavodoxin protein family. However, IMPORTANCEBrucella abortus is an etiological agent of brucellosis, which is among the most common zoonotic diseases worldwide. The general stress response (GSR) regulatory system of B. abortus controls the transcription of approximately 100 genes and is required for maintenance of chronic infection in a murine model; the majority of GSR-regulated genes remain uncharacterized. We present in vitro and in vivo functional and structural analyses of WrpA, whose expression is strongly induced by GSR under oxidative conditions. Though WrpA is structurally related to NADH:quinone oxidoreductases, it does not bind redox cofactors in solution, nor does it exhibit oxidoreductase activity in vitro. However, WrpA does affect spleen inflammation in a murine infection model. Our data provide evidence that WrpA forms a new functional class of WrbA/flavodoxin family proteins. Bacterial pathogens face fluctuating chemical and physical challenges in the host environment, including low pH, antimicrobial peptides, nutrient sequestration, and oxidative burst. These conditions can damage essential cellular components, including nucleic acids, proteins, and lipids. As such, bacteria encode a variety of protection mechanisms, including antioxidant enzymes, DNA damage repair systems, and efflux systems (1-4), which enable the cell to resist attacks by the host immune system (5-7).The diverse flavodoxin family, which is composed of enzymes that noncovalently bind a flavin cofactor and transfer electrons between a variety of substrates, can help to maintain cellular redox balance and confer resistance to oxidative stress (8-10). Flavodoxins and flavodoxin-like proteins are also known to promote pathogen virulence and to play a role in host infection and colonization (8,(11)(12)(13)(14)(15)(16)(17)(18), in addition to important roles in enzyme activation and metabolism (15). The flavodoxin-like protein WrbA (tryptophan [W] repressor binding protein) has been described for several microbial species, in which it is proposed to facilitate adaptation to varied chemical changes in the environment (13,(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)