The prominent alteration in transcriptome and metabolome of Mycobacterium bovis BCG str. Tokyo 172 induced by vitamin B1

Thiamine-biosynthesis genes Bbpyr and Bbthi are required for conidial production and cell wall integrity of the entomopathogenic fungus Beauveria bassiana

Beauveria bassiana is an important entomopathogenic fungus used to control a variety of insect pests. Conidia are the infective propagules of the fungus. However, some important factors that influence conidiation are still to be investigated. In this study, a mutant with decreased conidial production and hyphal growth was identified from a random T-DNA insertional library of B. bassiana. The corresponding gene (Bbthi) for this mutation encodes a putative thiazole synthase. Thiazole and pyrimidine are structural components of thiamine (vitamin B1), which is an essential nutrient for all forms of life. Disruption of Bbthi, Bbpyr, a putative pyrimidine synthetic gene, or both in B. bassiana results in a significant decrease of thiamine content. Loss of Bbthi and Bbpyr function significantly decreased the conidial production and hyphal growth, as well as disrupted the integrity of conidial cell wall. However, the defect of Bbpyr and Bbthi does not decrease the virulence of B. bassiana. Our results indicate the importance of thiamine biosynthesis in conidiation of B. bassiana, and provide useful information to produce conidia of entomopathogenic fungi for biocontrol of insect pests.

UPLC-orbitrap-MS-based metabolic profiling of HaCaT cells exposed to withanolides extracted from Datura metel.L: Insights from an untargeted metabolomics

In recent decades, more and more attention to the withanolides extracted from Datura metel.L has been paid due to their anti-psoriatic effects. Withanolides have also been reported to exhibit anti-inflammatory and anti-proliferative properties. Thus, withanolides have been considered as a promising candidate of anti-psoriatic drug. The aim of this study was to investigated the metabolic network of HaCaT cells after exposure to withanolides to identify anti-psoriatic mechanism induced by withanolides on skin cells. In this experiment, our results demonstrated that exposure to withanolides at concentrations beyond 50 μg/mL inhibited cell proliferation and induced cell apoptosis in a dose-dependent manner. In addition, withanolides-induced reactive oxygen species (ROS) generation and mitochondrial depolarization in HaCaT cells. In this research, ultra-high performance liquid chromatography coupled with orbitrap mass spectrometry (UPLC-orbitrap-MS) method was applied to profile metabolite changes in HaCaT cells exposed to withanolides. In total, significant variations in 38 differential metabolites were identified between withanolides exposure and untreated groups. The exposure of HaCaT cells to withanolides at the dose of 200 μg/mL for 24 h was revealed by the disturbance of energy metabolism, amino acid metabolism, lipid metabolism and nucleic acid metabolism. UPLC-orbitrap-MS-based cell metabolomics provided a comprehensive method for the identification of withanolides' anti-psoriasis mechanisms in vitro. And above metabolic disorders also reflected potential therapeutic targets for treating psoriasis.

Mycobacterial ethambutol responsive genes and implications in antibiotics resistance

Mycobacterium tuberculosis (M. tuberculosis), the causative agent of tuberculosis (TB), remains a formidable threat in mortality and morbidity worldwide. Ethambutol (EMB) is one of the first-line drugs regimens for TB treatment. Arabinosyl transferases are established targets of EMB, which is involved in the biosynthesis of arabinogalactan (AG) and lipoarabinomannan (LAM). Mutations among embCAB operon are responsible for around 70% clinical EMB resistant M. tuberculosis. In this review, we summarised other potential factors associated with EMB resistance via analysing whole genome, proteome and transcriptome of M. tuberculosis exposed to EMB. This will help to design better diagnosis of EMB resistance.

Revisiting the expression signature of pks15/1 unveils regulatory patterns controlling phenolphtiocerol and phenolglycolipid production in pathogenic mycobacteria

One of the most important and exclusive characteristics of mycobacteria is their cell wall. Amongst its constituent components are two related families of glycosylated lipids, diphthioceranates and phthiocerol dimycocerosate (PDIM) and its variant phenolic glycolipids (PGL). PGL have been associated with cell wall impermeability, phagocytosis, defence against nitrosative and oxidative stress and, intriguingly, biofilm formation. In bacteria from the Mycobacterium tuberculosis complex (MTBC), the biosynthetic pathway of the phenolphthiocerol moiety of PGL depends upon the expression of several genes encoding type I polyketide synthases (PKS), namely ppsA-E and pks15/1 which constitute the PDIM + PGL locus, and that are highly conserved in PDIM/PGL-producing strains. Consensus has not been achieved regarding the genetic organization of pks15/1 locus and knowledge is lacking on its transcriptional signature. Here we explore publicly available datasets of transcriptome data (RNA-seq) from more than 100 MTBC experiments in 40 growth conditions to outline the transcriptional structure and signature of pks15/1, using a differential expression approach to infer the regulatory patterns involving these and related genes. We show that pks1 expression is highly correlated with fadD22, Rv2949c, lppX, fadD29 and, also, pks6 and pks12, with the first three putatively integrating into a polycistronic structure. We evidence dynamic transcriptional heterogeneity within the genes involved in phenolphtiocerol and phenolic glycolipid production, most exhibiting up-regulation upon acidic pH and antibiotic exposure and down-regulation under hypoxia, dormancy, and low/high iron concentration. We finally propose a model based on transcriptome data in which σD positively regulates pks1, pks15 and fadD22, while σB and σE factors exert negative regulation at an upper level.

Vitamin B and Vitamin C Affect DNA Methylation and Amino Acid Metabolism in Mycobacterium bovis BCG

Vitamins are essential nutrients and key cofactors of enzymes that regulate cellular metabolism, and also activate the immune system. Recent studies have shown that vitamin B1 (V_{B 1}) and vitamin C (Vc) can inhibit Mycobacterium tuberculosis growth, but the precise mechanism is still not well understood. In the present study, we have used RNA-sequencing (RNA-seq), liquid chromatography coupled to mass spectrometry (LC-MS) and single-molecule real-time (SMRT) sequencing to analyze the transcriptional, metabolic and methylation profiles of Mycobacterium bovis BCG when treated with V_{B 1} and Vc. Our results show that, after vitamin treatment, variant metabolites were mainly clustered in pathways related to amino acid metabolism. Treatment with both vitamins significantly up-regulated the gene encoding cysteine synthase A. Additionally, only BCG that was treated with V_C showed m4c modifications. Genes harboring this methylation were up-regulated, suggesting that m4c methylation can promote gene transcription to some extent. Overall, this study contributes to the understanding of the effects of V_{B 1} and V_C, and suggests that these vitamins constitute potential anti-tuberculosis drugs.