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Root-associated bacteria community characteristics of two Antarctic plants - Deschampsia antarctica and Colobanthus quitensis – a comparison
Get PDFColobanthus quitensis and Deschampsia antarctica are the only angiosperms to naturally colonize the Antarctic region. The reason for their sole presence in Antarctica is still debated as there is no definitive consensus on how only two unrelated flowering plants managed to establish a breeding population in this part of the World. In this study, we have explored and compared the rhizosphere and root-endosphere dwelling microbial community of C. quitensis and D. antarctica specimens sampled in maritime Antarctica from sites displaying contrasting edaphic characteristics. Bacterial phylogenetic diversity (high throughput 16S rRNA gene fragment targeted sequencing) and microbial metabolic activity (Biolog Ecoplates) with a geochemical soil background were assessed. Gathered data showed that the microbiome of C. quitensis root system was mostly site-dependent, displaying different characteristics in each of the examined locations. This plant tolerated an active bacterial community only in severe conditions (salt stress, nutrient depravation) while in other, more favorable circumstances it restricted microbial activity, with a possibility of microbivory-based nutrient acquisition. The microbial communities of D. antarctica showed a high degree of similarity between samples within a particular rhizocompartment. The grass’ endosphere was significantly enriched in plant beneficial taxa of the family Rhizobiaceae, which displayed obligatory endophyte characteristics, suggesting that at least part of this community is transmitted vertically. Ultimately, the ecological success of C. quitensis and D. antarctica in Antarctica might be largely attributed to their associations and management of root-associated microbiota
The AraC-Type Transcriptional Regulator GliR (PA3027) Activates Genes of Glycerolipid Metabolism in Pseudomonas aeruginosa
Get PDFPseudomonas aeruginosa encodes a large set of transcriptional regulators (TRs) that modulate
and manage cellular metabolism to survive in variable environmental conditions including that of
the human body. The AraC family regulators are an abundant group of TRs in bacteria, mostly acting
as gene expression activators, controlling diverse cellular functions (e.g., carbon metabolism, stress
response, and virulence). The PA3027 protein from P. aeruginosa has been classified in silico as a
putative AraC-type TR. Transcriptional profiling of P. aeruginosa PAO1161 overexpressing PA3027
revealed a spectacular increase in the mRNA levels of PA3026-PA3024 (divergent to PA3027), PA3464,
and PA3342 genes encoding proteins potentially involved in glycerolipid metabolism. Concomitantly,
chromatin immunoprecipitation-sequencing (ChIP-seq) analysis revealed that at least 22 regions are
bound by PA3027 in the PAO1161 genome. These encompass promoter regions of PA3026, PA3464,
and PA3342, showing the major increase in expression in response to PA3027 excess. In Vitro DNA
binding assay confirmed interactions of PA3027 with these regions. Furthermore, promoter-reporter
assays in a heterologous host showed the PA3027-dependent activation of the promoter of the
PA3026-PA3024 operon. Two motifs representing the preferred binding sites for PA3027, one localized
upstream and one overlapping with th
Terpenoid Biosynthesis Dominates among Secondary Metabolite Clusters in Mucoromycotina Genomes
Get PDFEarly-diverging fungi harbour unprecedented diversity in terms of living forms, biological traits and genome architecture. Before the sequencing era, non-Dikarya fungi were considered unable to produce secondary metabolites (SM); however, this perspective is changing. The main classes of secondary metabolites in fungi include polyketides, nonribosomal peptides, terpenoids and siderophores that serve different biological roles, including iron chelation and plant growth promotion. The same classes of SM are reported for representatives of early-diverging fungal lineages. Encouraged by the advancement in the field, we carried out a systematic survey of SM in Mucoromycotina and corroborated the presence of various SM clusters (SMCs) within the phylum. Among the core findings, considerable representation of terpene and nonribosomal peptide synthetase (NRPS)-like candidate SMCs was found. Terpene clusters with diverse domain composition and potentially highly variable products dominated the landscape of candidate SMCs. A uniform low-copy distribution of siderophore clusters was observed among most assemblies. Mortierellomycotina are highlighted as the most potent SMC producers among the Mucoromycota and as a source of novel peptide products. SMC identification is dependent on gene model quality and can be successfully performed on a batch scale with genomes of different quality and completeness
The MarR-Type Regulator PA3458 Is Involved in Osmoadaptation Control in Pseudomonas aeruginosa
Get PDFPseudomonas aeruginosa is a facultative human pathogen, causing acute and chronic infections
that are especially dangerous for immunocompromised patients. The eradication of P.
aeruginosa is difficult due to its intrinsic antibiotic resistance mechanisms, high adaptability, and
genetic plasticity. The bacterium possesses multilevel regulatory systems engaging a huge repertoire
of transcriptional regulators (TRs). Among these, the MarR family encompasses a number of proteins,
mainly acting as repressors, which are involved in response to various environmental signals. In
this work, we aimed to decipher the role of PA3458, a putative MarR-type TR from P. aeruginosa.
Transcriptional profiling of P. aeruginosa PAO1161 overexpressing PA3458 showed changes in the
mRNA level of 133 genes; among them, 100 were down-regulated, suggesting the repressor function
of PA3458. Concomitantly, ChIP-seq analysis identified more than 300 PA3458 binding sites in
P. aeruginosa. The PA3458 regulon encompasses genes involved in stress response, including the
PA3459–PA3461 operon, which is divergent to PA3458. This operon encodes an asparagine synthase,
a GNAT-family acetyltransferase, and a glutamyl aminopeptidase engaged in the production of
N-acetylglutaminylglutamine amide (NAGGN), which is a potent bacterial osmoprotectant. We
showed that PA3458-mediated control of PA3459–PA3461 expression is required for the adaptation
of P. aeruginosa growth in high osmolarity. Overall, our data indicate that PA3458 plays a role in
osmoadaptation control in P. aeruginosa
Increased DNA repair capacity augments resistance of glioblastoma cells to photodynamic therapy
No full textPhotodynamic therapy (PDT) is a clinically approved cancer therapy of low invasiveness. The therapeutic procedure involves administering a photosensitizing drug (PS), which is then activated with monochromatic light of a specific wavelength. The photochemical reaction produces highly toxic oxygen species. The development of resistance to PDT in some cancer cells is its main limitation. Several mechanisms are known to be involved in the development of cellular defense against cytotoxic effects of PDT, including activation of antioxidant enzymes, drug efflux pumps, degradation of PS, and overexpression of protein chaperons. Another putative factor that plays an important role in the development of resistance of cancer cells to PDT seems to be DNA repair; however, it has not been well studied so far. To explore the role of DNA repair and other potential novel mechanisms associated with the resistance to PDT in the glioblastoma cells, cells stably resistant to PDT were isolated from PDT sensitive cells following repetitive PDT cycles. Duly characterization of isolated PDT-resistant glioblastoma revealed that the resistance to PDT might be a consequence of several mechanisms, including higher repair efficiency of oxidative DNA damage and repair of DNA breaks. Higher activity of APE1 endonuclease and increased expression and activation of DNA damage kinase ATM was demonstrated in the U-87 MGR cell line, suggesting and proving that they are good targets for sensitization of resistant cells to PDT
Lactococcus lactis resistance to aureocin A53- and enterocin L50-like bacteriocins and membrane-targeting peptide antibiotics relies on the YsaCB-KinG-LlrG four-component system
Get PDFResistance to non-ribosomally synthesized peptide antibiotics affecting the cell envelope is well-studied and mostly associated with the action of peptide-sensing and detoxification (PSD) modules which consist of a two-component system (TCS) and an ATP-binding cassette (ABC) transporter. In contrast, the resistance mechanisms to ribosomally synthesized bacterial toxic peptides (bacteriocins), which also affect the cell envelope, are studied to lesser extent, and possible cross-resistance between them and antibiotics is still poorly understood. In the present study, we investigated the development of resistance of Lactococcus lactis to aureocin A53- and enterocin L50-like bacteriocins and cross-resistance with antibiotics. First, 19 spontaneous mutants resistant to their representatives were selected and displayed changes in the sensitivity also to peptide antibiotics acting on the cell envelope (bacitracin, daptomycin, and gramicidin). Sequencing of their genomes revealed mutations in genes encoding ABC transporter YsaCB and TCS KinG-LlrG, the emergence of which induced upregulation of the dltABCD and ysaDCB operons. The ysaB mutations were either nonsense or frameshift and led to the generation of truncated YsaB but with the conserved N-terminal FtsX domain intact. Deletions of ysaCB or llrG had a minor effect on the resistance of the obtained mutants to the tested bacteriocins, daptomycin, and gramicidin, indicating that the development of resistance is dependent on the modification of the protein rather than its absence. In further corroboration of the above conclusion, we show that the FtsX domain, which functions effectively when the YsaB is lacking its central and C-terminal parts, is critical for the resistance to these antimicrobials
Multi-omic signatures of atherogenic dyslipidaemia: pre-clinical target identification and validation in humans
Get PDFBackground: Dyslipidaemia is a major risk factor for atherosclerosis and cardiovascular diseases. The molecular
mechanisms that translate dyslipidaemia into atherogenesis and reliable markers of its progression are yet to be fully
elucidated. To address this issue, we conducted a comprehensive metabolomic and proteomic analysis in an experi‑
mental model of dyslipidaemia and in patients with familial hypercholesterolemia (FH).
Methods: Liquid chromatography/mass spectrometry (LC/MS) and immunoassays were used to fnd out blood
alterations at metabolite and protein levels in dyslipidaemic ApoE−/−/LDLR−/− mice and in FH patients to evaluate
their human relevance.
Results: We identifed 15 metabolites (inhibitors and substrates of nitric oxide synthase (NOS), low-molecular-weight
antioxidants (glutamine, taurine), homocysteine, methionine, 1-methylnicotinamide, alanine and hydroxyproline) and
9 proteins (C-reactive protein, proprotein convertase subtilisin/kexin type 9, apolipoprotein C-III, soluble intercellular
adhesion molecule-1, angiotensinogen, paraoxonase-1, fetuin-B, vitamin K-dependent protein S and biglycan) that
diferentiated FH patients from healthy controls. Most of these changes were consistently found in dyslipidaemic mice
and were further amplifed if mice were fed an atherogenic (Western or low-carbohydrate, high-protein) diet.
Conclusions: The alterations highlighted the involvement of an immune-infammatory response system, oxidative
stress, hyper-coagulation and impairment in the vascular function/regenerative capacity in response to dyslipidaemia
that may also be directly engaged in development of atherosclerosis. Our study further identifed potential biomark‑
ers for an increased risk of atherosclerosis that may aid in clinical diagnosis or in the personalized treatment.
Keywords: Dyslipidaemia, Atherosclerosis, Metabolome, Proteome, Pathological mechanisms, Serological biomarker
Interactions of Bacteriophages with Animal and Human Organisms—Safety Issues in the Light of Phage Therapy
Get PDFBacteriophages are viruses infecting bacterial cells. Since there is a lack of specific receptors for bacteriophages on eukaryotic cells, these viruses were for a long time considered to be neutral to animals and humans. However, studies of recent years provided clear evidence that bacteriophages can interact with eukaryotic cells, significantly influencing the functions of tissues, organs, and systems of mammals, including humans. In this review article, we summarize and discuss recent discoveries in the field of interactions of phages with animal and human organisms. Possibilities of penetration of bacteriophages into eukaryotic cells, tissues, and organs are discussed, and evidence of the effects of phages on functions of the immune system, respiratory system, central nervous system, gastrointestinal system, urinary tract, and reproductive system are presented and discussed. Modulations of cancer cells by bacteriophages are indicated. Direct and indirect effects of virulent and temperate phages are discussed. We conclude that interactions of bacteriophages with animal and human organisms are robust, and they must be taken under consideration when using these viruses in medicine, especially in phage therapy, and in biotechnological application
Yeast Models and Molecular Mechanisms of Neurodegenerative Diseases
Get PDFNeurodegenerative diseases are a group of age-related diseases and a growing problem in an aging society. In addition to major neurodegenerative diseases, such as Alzheimer’s, Parkinson’s, and Huntington’s diseases, there are numerous rare and even ultra-rare ones. These diseases are a consequence of diverse pathological genetic and physiological alterations in cells but manifest by common dysfunctions of the central or peripheral nervous systems. Interestingly, in a group of genes linked to neurodegenerative diseases, the genes affecting mitochondria are overrepresented [1]. Moreover, even though the primary mutation does not affect mitochondria directly, the mitochondria are often disturbed. This probably indicates that because of high demand for ATP, mitochondria are crucial for neurons. In the group of genes affecting the mitochondria are also those that code for proteins responsible for the formation or functioning of membrane contact sites (MCSs) between the mitochondria and other organelles [2,3,4,5]. MCSs are sites of inter-organellar communication with various functions, such as lipid and metabolite exchange, organelle dynamics, positioning, distribution, and clearance. MCSs between mitochondria and the endoplasmic reticulum (ER) are also especially important for maintaining calcium ion (Ca2+) homeostasis. Thus, mitochondrial MCSs disturbance affects mitochondrial biogenesis and functions
ApoE4 disrupts interaction of sortilin with fatty acid-binding protein 7 essential to promote lipid signaling
Get PDFSortilin is a neuronal receptor for apolipoprotein E (apoE). Sortilin-dependent uptake of lipidated apoE promotes conversion of polyunsaturated fatty acids (PUFA) into neuromodulators that induce anti-inflammatory gene expression in the brain. This neuroprotective pathway works with the apoE3 variant but is lost with the apoE4 variant, the main risk factor for Alzheimer's disease (AD). Here, we elucidated steps in cellular handling of lipids through sortilin, and why they are disrupted by apoE4. Combining unbiased proteome screens with analyses in mouse models, we uncover interaction of sortilin with fatty acid-binding protein 7 (FABP7), the intracellular carrier for PUFA in the brain. In the presence of apoE3, sortilin promotes functional expression of FABP7 and its ability to elicit lipid-dependent gene transcription. By contrast, apoE4 binding blocks sortilin-mediated sorting, causing catabolism of FABP7 and impairing lipid signaling. Reduced FABP7 levels in the brain of AD patients expressing apoE4 substantiate the relevance of these interactions for neuronal lipid homeostasis. Taken together, we document interaction of sortilin with mediators of extracellular and intracellular lipid transport that provides a mechanistic explanation for loss of a neuroprotective lipid metabolism in AD