MbovP0725, a secreted serine/threonine phosphatase, inhibits the host inflammatory response and affects metabolism in Mycoplasma bovis

Mycoplasma species are able to produce and release secreted proteins, such as toxins, adhesins, and virulence-related enzymes, involved in bacteria adhesion, invasion, and immune evasion between the pathogen and host. Here, we investigated a novel secreted protein, MbovP0725, from Mycoplasma bovis encoding a putative haloacid dehalogenase (HAD) hydrolase function of a key serine/threonine phosphatase depending on Mg2+ for the dephosphorylation of its substrate pNPP, and it was most active at pH 8 to 9 and temperatures around 40°C. A transposon insertion mutant strain of M. bovis HB0801 that lacked the protein MbovP0725 induced a stronger inflammatory response but with a partial reduction of adhesion ability. Using transcriptome sequencing and quantitative reverse transcription polymerase chain reaction analysis, we found that the mutant was upregulated by the mRNA expression of genes from the glycolysis pathway, while downregulated by the genes enriched in ABC transporters and acetate kinase-phosphate acetyltransferase pathway. Untargeted metabolomics showed that the disruption of the Mbov_0725 gene caused the accumulation of 9-hydroxyoctadecadienoic acids and the consumption of cytidine 5'-monophosphate, uridine monophosphate, and adenosine monophosphate. Both the exogenous and endogenous MbvoP0725 protein created by purification and transfection inhibited lipopolysaccharide (LPS)-induced IL-1β, IL-6, and TNF-α mRNA production and could also attenuate the activation of MAPK-associated pathways after LPS treatment. A pull-down assay identified MAPK p38 and ERK as potential substrates for MbovP0725. These findings define metabolism- and virulence-related roles for a HAD family phosphatase and reveal its ability to inhibit the host pro-inflammatory response.

IMPORTANCE

Mycoplasma bovis (M. bovis) infection is characterized by chronic pneumonia, otitis, arthritis, and mastitis, among others, and tends to involve the suppression of the immune response via multiple strategies to avoid host cell immune clearance. This study found that MbovP0725, a haloacid dehalogenase (HAD) family phosphatase secreted by M. bovis, had the ability to inhibit the host pro-inflammatory response induced by lipopolysaccharide. Transcriptomic and metabolomic analyses were used to identify MbovP0725 as an important phosphatase involved in glycolysis and nucleotide metabolism. The M. bovis transposon mutant strain T8.66 lacking MbovP0725 induced a higher inflammatory response and exhibited weaker adhesion to host cells. Additionally, T8.66 attenuated the phosphorylation of MAPK P38 and ERK and interacted with the two targets. These results suggested that MbovP0725 had the virulence- and metabolism-related role of a HAD family phosphatase, performing an anti-inflammatory response during M. bovis infection.

Genome-Wide Identification and Analysis of Stress Response of Trehalose-6-Phosphate Synthase and Trehalose-6-Phosphate Phosphatase Genes in Quinoa

Saline-alkali stress seriously affects the yield and quality of crops, threatening food security and ecological security. Improving saline-alkali land and increasing effective cultivated land are conducive to sustainable agricultural development. Trehalose, a nonreducing disaccharide, is closely related to plant growth and development and stress response. Trehalose 6-phosphate synthase (TPS) and trehalose-6-phosphate phosphatase (TPP) are key enzymes catalyzing trehalose biosynthesis. To elucidate the effects of long-term saline-alkali stress on trehalose synthesis and metabolism, we conducted an integrated transcriptome and metabolome analysis. As a result, 13 TPS and 11 TPP genes were identified in quinoa (Chenopodium quinoa Willd.) and were named CqTPS1-13 and CqTPP1-11 according to the order of their Gene IDs. Through phylogenetic analysis, the CqTPS family is divided into two classes, and the CqTPP family is divided into three classes. Analyses of physicochemical properties, gene structures, conservative domains and motifs in the proteins, and cis-regulatory elements, as well as evolutionary relationships, indicate that the TPS and TPP family characteristics are highly conserved in quinoa. Transcriptome and metabolome analyses of the sucrose and starch metabolism pathway in leaves undergoing saline-alkali stress indicate that CqTPP and Class II CqTPS genes are involved in the stress response. Moreover, the accumulation of some metabolites and the expression of many regulatory genes in the trehalose biosynthesis pathway changed significantly, suggesting the metabolic process is important for the saline-alkali stress response in quinoa.

Integrated Transcriptome and Metabolome Analysis of Rice Leaves Response to High Saline-Alkali Stress

Rice (Oryza sativa) is one of the most important crops grown worldwide, and saline-alkali stress seriously affects the yield and quality of rice. It is imperative to elucidate the molecular mechanisms underlying rice response to saline-alkali stress. In this study, we conducted an integrated analysis of the transcriptome and metabolome to elucidate the effects of long-term saline-alkali stress on rice. High saline-alkali stress (pH > 9.5) induced significant changes in gene expression and metabolites, including 9347 differentially expressed genes (DEGs) and 693 differentially accumulated metabolites (DAMs). Among the DAMs, lipids and amino acids accumulation were greatly enhanced. The pathways of the ABC transporter, amino acid biosynthesis and metabolism, glyoxylate and dicarboxylate metabolism, glutathione metabolism, TCA cycle, and linoleic acid metabolism, etc., were significantly enriched with DEGs and DAMs. These results suggest that the metabolites and pathways play important roles in rice's response to high saline-alkali stress. Our study deepens the understanding of mechanisms response to saline-alkali stress and provides references for molecular design breeding of saline-alkali resistant rice.

Transcriptomic and Metabonomic Profiling Reveals the Antihyperlipidemic Effects of Tartary Buckwheat Sprouts in High-Fat-Diet-Fed Mice

Flavonoids are known for potent antioxidant activity and antihyperlipidemia. As a result of the few antinutritional factors and high bioactive substances, such as flavonoids, sprouts of tartary buckwheat (Fagopyrum tataricum, STB) have become healthy food. This study aims to unravel the antihyperlipidemic effects of STB in vivo and its potential mechanism through transcriptomic and metabonomic analysis. The physiological parameters of mice administered the high-fat diet with or without 2.5 and 5% of STB for 10 weeks were recorded. Liquid chromatography-tandem mass spectrometry and RNA sequencing were applied to obtain the serum lipid metabolomic and hepatic transcriptomic profiling, respectively. Results revealed that STB could significantly alleviate the increase of body weight, liver, and abdominal adipose while ameliorating the lipid content in serum and insulin resistance of mice fed with a high-fat diet. Notably, the metabonomic analysis identified the core differential metabolites mainly enriched in the pathways, such as fat digestion and absorption, insulin resistance, and other processes. Transcriptomic results revealed that STB significantly altered the expression levels of PIK3R1, LRP5, SLC10A2, and FBXO21. These genes are involved in the PI3K-AKT signaling pathway, digestion and absorption of carbohydrates, and type II diabetes mellitus pathways. In this study, STB exhibited remarkable influence on the metabolism of lipids and glucose, exerting antihyperlipidemic effects. STB have the potential for the development and application of a lipid-lowering health food.

Large-Scale Modeling Approach Reveals Functional Metabolic Shifts during Hepatic Differentiation

Being able to explore the metabolism of broad metabolizing cells is of critical importance in many research fields. This article presents an original modeling solution combining metabolic network and omics data to identify modulated metabolic pathways and changes in metabolic functions occurring during differentiation of a human hepatic cell line (HepaRG). Our results confirm the activation of hepato-specific functionalities and newly evidence modulation of other metabolic pathways, which could not be evidenced from transcriptomic data alone. Our method takes advantage of the network structure to detect changes in metabolic pathways that do not have gene annotations and exploits flux analyses techniques to identify activated metabolic functions. Compared to the usual cell-specific metabolic network reconstruction approaches, it limits false predictions by considering several possible network configurations to represent one phenotype rather than one arbitrarily selected network. Our approach significantly enhances the comprehensive and functional assessment of cell metabolism, opening further perspectives to investigate metabolic shifts occurring within various biological contexts.