Whole-genome resequencing of Pseudomonas aeruginosa PAO1 after anti-virulence treatments targeting iron uptake
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ABSTRACT: We carried out an experimental evolution in human serum as an ex-vivo model and screened evolved lines for the evolution of resistance phenotypes towards two anti-virulence treatments, gallium and flucytosine, which both target the iron scavenging pyoverdine of Pseudomonas aeruginosa (each at 2 different doses). We performed whole-genome sequencing of 16 evolved clones from the different treatment regimes .
Project description:Nutrient starvation is an important survival challenge for bacteria during industrial production of functional foods. Lactobacilli are increasingly being used as probiotics in functional foods. As next-generation sequencing technology has greatly advanced, we performed integrative proteomic and genomic analysis to investigate the response of Lactobacillus casei Zhang to a glucose-restricted environment. L. casei Zhang strains were permitted to evolve in glucose-limited or normal medium from a common ancestor over a 3-year period, and they were sampled after 1000, 2000, 3000, 4000, 5000, 6000, 7000, and 8000 generations and subjected to proteomic and genomic analyses. Genomic resequencing data revealed different point mutations and other mutational events in each generation of L. casei Zhang under glucose limitation stress. The proteins expressed differentially under glucose limitation were found to be significantly related to fructose and mannose metabolism, carbohydrate metabolic processes, lyase activity, and amino acid-transporting ATPase activity. The integrative proteomic and genomic analysis revealed that the mutations protected L. casei Zhang against glucose starvation by regulating other cellular carbohydrate, fatty acid, and amino acid catabolism; phosphoenolpyruvate system pathway activation; glycogen synthesis; ATP consumption; pyruvate metabolism; and general stress response protein expression. The results help reveal the mechanisms of adapting to glucose starvation and provide new strategies for enhancing the industrial utility of L. casei Zhang.
Project description:Analysis of copy number variation in evolved haploid, diploid, tetraploid strains. All experimental samples were compared to the same reference strain S288C. The samples include the progenitor strains for the haploid, diploid, and tetraploid evolution experiments, and single colony isolates (clones) from the evolving populations at given time points. Evolved clones were analyzed at generation 250 unless the name is followed by gen35, gen55 or gen500, in which case those generations were analyzed.
Project description:To investigate how organisms mitigate the deleterious effects of mistranslation during evolution, a mutant tRNA was expressed in S. cerevisiae. The expression of Candida Ser-tRNACAG from a low copy plasmid in S. cerevisiae promoted mistranslation events by random incorporation of both serine and leucine at CUG codons. As mistranslation causes an overload of the protein quality pathways, it disrupts cellular protein homeostasis leading to a major fall in fitness. Laboratory evolutionary experiments were performed to study whether the fitness cost of mistranslation can be lowered. We also wanted to identify the cost-reduction strategy: reducing the frequencies of errors (mitigation), or increasing tolerance to errors (robustness), either by global or local activities. Gene expression was measured in the ancestor (non-evolved) lineage in two different situations: 1) carrying an empty vector and 2) expressing the mutant Ser-tRNACAG. Gene expression was also measured in three ambiguously evolved lineages (B3, D11, H9) in both situations (carrying an empty vector and expressing the mutant tRNA). Three independent experiments were performed for each lineage. Non-evolved strain with empty vector was used as control sample.
Project description:In some of the earliest uses of genome-wide gene-expression microarrays and array-based Comparative Genomic Hybridization (aCGH), a set of diploid yeasts that had undergone experimental evolution under aerobic glucose limitation was used to explore how gene expression and genome structure had responded to this selection pressure. To more deeply understand how adaptation to one environment might constrain or enhance performance in another we have now identified the adaptive mutations in this set of clones using whole-genome sequencing, and have assessed whether the evolved clones had become generalists or specialists by assaying their fitness under three contrasting growth environments: aerobic and anaerobic glucose limitation and aerobic acetate limitation. Additionally, evolved clones and their common ancestor were assayed for gene expression, biomass estimates and residual substrate levels under the alternative growth conditions. Relative fitnesses were evaluated by competing each clone against a common reference strain in each environment. Unexpectedly, we found that the evolved clones also outperformed their ancestor under strictly fermentative and strictly oxidative growth conditions. We conclude that yeasts evolving under aerobic glucose limitation become generalists for carbon limitation, as the mutations selected for in one environment are advantageous in others. High-throughput sequencing of the evolved clones uncovered mutations in genes involved in glucose sensing, signaling, and transport that in part explain these physiological phenotypes, with different sets of mutations found in independently-evolved clones. Earlier gene expression data from aerobic glucose-limited cultures had revealed a shift from fermentation towards respiration in all evolved clones explaining increased fitness in that condition. However, because the evolved clones also show higher fitness under strictly anaerobic conditions and under conditions requiring strictly respirative growth, this switch cannot be the sole source of adaptive benefit. Furthermore, because independently evolved clones are genetically distinct we conclude that there are multiple mutational paths leading to the generalist phenotype. Strain Name: Parental strain (CP1AB) or evolved clones (E1 - E5) Media: aerobic / anaerobic 36 hybridizations
Project description:We created a mutator protein. The mutator, was prepared by fusing a PmCDA1 (Petromyzon marinus Cytidine DeAminase) and E.coli RNA polymerase alpha subunit(EcoRNAP alpha). After 120 cycles, whole genome sequencing was performed on the wild type and evolved sample. After characterization of the mutation capacity of our mutator, we evolved a sucrose utilization strain and we sequenced Suc strain.
Project description:The mechanism of evolution in different conditions can be examined from various molecular aspects that constitute a cell, namely, transcript, protein or metabolite abundance. We have analyzed transcript and metabolite abundance changes in evolved and ancestor strains in three different evolutionary conditions, namely, excess-nutrient adaptation, prolonged stationary phase adaptation and adaptation due to environmental shift, in two different strains of Escherichia coli K-12 (MG1655 and DH10B).
Project description:One of the central goals of evolutionary biology is to explain and predict the molecular basis of adaptive evolution. We studied the evolution of genetic networks in Saccharomyces cerevisiae (budding yeast) populations propagated for more than 200 generations in different nitrogen-limiting conditions. We find that rapid adaptive evolution in nitrogen-poor environments is dominated by the de novo generation and selection of copy number variants (CNVs), a large fraction of which contain genes encoding specific nitrogen transporters including PUT4, DUR3 and DAL4. The large fitness increases associated with these alleles limits the genetic heterogeneity of adapting populations even in environments with multiple nitrogen sources. Complete identification of acquired point mutations, in individual lineages and entire populations, identified heterogeneity at the level of genetic loci but common themes at the level of functional modules, including genes controlling phosphatidylinositol-3-phosphate metabolism and vacuole biogenesis. Adaptive strategies shared with other nutrient-limited environments point to selection of genetic variation in the TORC1 and Ras/PKA signaling pathways as a general mechanism underlying improved growth in nutrient-limited environments. Within a single population we observed the repeated independent selection of a multi-locus genotype, comprised of the functionally related genes GAT1, MEP2 and LST4. By studying the fitness of individual alleles, and their combination, as well as the evolutionary history of the evolving population, we find that the order in which these mutations are acquired is constrained by epistasis. The identification of repeatedly selected variation at functionally related loci that interact epistatically suggests that gene network polymorphisms (GNPs) may be a frequent outcome of adaptive evolution. Our results provide insight into the mechanistic basis by which cells adapt to nutrient-limited environments and suggest that knowledge of the selective environment and the regulatory mechanisms important for growth and survival in that environment greatly increases the predictability of adaptive evolution. DNA from each evolved clone or population is hybridized vs DNA from the ancestral strain
Project description:When the survivors of antibiotic treatment (persisters) are repeatedly regrown and retreated with the same antibiotic for several cycles, the new population will soon adapt to the treatment condition and become tolerant to the drug. Here, we did evolution experiments on Escherichia coli populations by treating it with daily high concentration of different antibiotics (ampicillin, ciprofloxacin and apramycin) approximating clinical dosage, during the rapid growth-exponential phase. After a few cycles, we observed that the evolved populations exhibit extremely high tolerance to the drug, which are achieved by single point mutations in one of several genes. Interestingly, treatment with different antibiotics led to the selection of different mutants despite the shared persistence phenotype. Here, we applied spectral counting-based quantitative proteomics to study the proteome profile of the evolved E. coli populations from different cyclic antibiotic treatments.
Project description:Adaptive evolution is generally assumed to progress through the accumulation of beneficial mutations. However, deleterious mutations may also have an important role by promoting adaptive genetic changes that are otherwise inaccessible. Here we study the capacity of the bakerM-bM-^@M-^Ys yeast genome to compensate the complete loss of genes during evolution, and explore the long-term consequences of this process. We initiated laboratory evolutionary experiments with over 180 haploid yeast genotypes, all of which initially displayed slow growth due to the deletion of a single gene. Compensatory adaptation was rapid and pervasive, and it promoted the genomic divergence of parallel evolving populations. The accumulated mutations did not restore wild type genomic expression states and generated diverse growth phenotypes across environments. Taken together, gene loss initiates genomic changes that can influence evolutionary potential upon environmental change. Evolved yeast-lines were generated by growing strains for 400 doublings during 104 days on YPD medium in 96 wells plates, 8 evolved lines were selected for microarray analysis. Two independent colonies of the wild type control, evolved and corresponding ancestor knock-out strains were grown to early midlog and used for transcription profiling by dual channel array against a common reference.
Project description:Metastasis poses a major challenge in cancer management, including EML4-ALK-rearranged non-small cell lung cancer (NSCLC). As cell migration is a critical step during metastasis, we assessed the anti-migratory activities of several clinical ALK inhibitors in NSCLC cells and observed differential anti-migratory capabilities despite similar ALK inhibition, with brigatinib displaying superior anti-migratory effects over other ALK inhibitors. Applying an unbiased in-situ mass spectrometry-based chemoproteomics approach, we determined the proteome-wide target profile of brigatinib in EML4-ALK+ NSCLC cells. Dose-dependent and cross-competitive chemoproteomics suggested MARK2 and MARK3 as relevant brigatinib kinase targets. Functional validation showed that combined pharmacological inhibition or genetic modulation of MARK2/3 inhibited cell migration. Consistently, brigatinib treatment induced inhibitory YAP1 phosphorylation downstream of MARK2/3. Collectively, our data suggest that brigatinib exhibits unusual cross-phenotype polypharmacology as despite similar efficacy for inhibiting EML4-ALK-dependent cell proliferation as other ALK inhibitors, it more effectively prevented migration of NSCLC cells due to co-targeting of MARK2/3.