Project description:Directed evolution in mammalian cells can facilitate the engineering of mammalian-compatible biomolecules and can enable synthetic evolvability for mammalian cells. We engineered an orthogonal alphaviral RNA replication system to evolve synthetic RNA-based devices, enabling RNA replicase-assisted continuous evolution (REPLACE) in live mammalian cells. we employed REPLACE to drive the continuous intracellular evolution of the cancer-related protein MEK1 with the aim of conferring resistance to Cobimetinib. To investigate the accumulation of mutations during this evolutionary process, we conducted amplicon sequencing on experimental materials collected at different stages. The results revealed intricate relationships among different mutations, highlighting the complex nature of the evolutionary landscape.
Project description:A dominant-negative gene therapy approach has been proposed and tested on proto-oncogene KRAS, wherein the oncogenic activity (and cell proliferation) of KRAS can be suppressed by introducing a dominant-negative KRAS allele (S17N). We employed REPLACE to conduct continuous evolution on KRAS (S17N) and examined its potential pathways for conferring resistance in this gene therapy methodology.To explore the accumulation of mutations in various RNAs during the KRAS (S17N) evolution experiment, we established a barcoded library and conducted lineage tracing of replicative RNAs carrying KRAS (S17N) throughout the evolution process.
Project description:The present study was aimed at analyzing (i) the biological cost of RNA polymerase (rpoB) mutations conferring rifampin resistance on H.pylori, (ii) the relationship between the cost of rpoB mutations and the chromosomal mutaion, (iii) the relationship between the cost of rpoB mutations and the transcription profile of sensitive and resistantrif strains of H.pylori (iv) and rpoB mutations in view of the possible fitness burden associated with resistance to another antibiotics. H.pylori reference strain 26695 was routinely maintained on Columbia agar plates and H. pylori-selective antibiotic mix Dent. Liquid culture was grown in BHI broth. Both plates and broth cultures were incubated at 37C under atmosphere enriched with 5% CO2 for 2-3 days . Mutant strains were selected by culturing H. pylori 26695 on selective plates containing rifampicin. In 5 days resistant colonies were picked up and passed under rifampicin pressure. RNA isolated was reverse transcribed and used to probe H. pylori home-made arrays
Project description:Based on a simple E.coli growth inhibition assay, the authors trained a model capable of identifying antibiotic potential in compounds structurally divergent from conventional antibiotic drugs. One of the predicted active molecules, Halicin (SU3327), was experimentally validated in vitro and in vivo.
Model Type: Predictive machine learning model.
Model Relevance: Probability that a compound inhibits E.coli growth.
Model Encoded by: Miquel Duran-Frigola(Ersilia)
Metadata Submitted in BioModels by: Zainab Ashimiyu-Abdusalam
Implementation of this model code by Ersilia is available here:
https://github.com/ersilia-os/eos4e40
Project description:A dominant-negative gene therapy approach has been proposed and tested on proto-oncogene KRAS, wherein the oncogenic activity (and cell proliferation) of KRAS can be suppressed by introducing a dominant-negative KRAS allele (S17N). We employed REPLACE to conduct continuous evolution on KRAS (S17N) and examined its potential pathways for conferring resistance in this gene therapy methodology.
Project description:Cationic antimicrobial peptides (CAPs) are promising novel alternatives to conventional antibacterial agents, but the overlap in resistance mechanisms between small-molecule antibiotics and CAPs is unknown. Does evolution of antibiotic resistance decrease (cross-resistance) or increase (collateral sensitivity) susceptibility to CAPs? We systematically addressed this issue by studying the susceptibilities of a comprehensive set of antibiotic resistant Escherichia coli strains towards 24 antimicrobial peptides. Strikingly, antibiotic resistant bacteria frequently showed collateral sensitivity to CAPs, while cross-resistance was relatively rare. We identified clinically relevant multidrug resistance mutations that simultaneously elevate susceptibility to certain CAPs. Transcriptome and chemogenomic analysis revealed that such mutations frequently alter the lipopolysaccharide composition of the outer cell membrane and thereby increase the killing efficiency of membrane-interacting antimicrobial peptides. Furthermore, we identified CAP-antibiotic combinations that rescue the activity of existing antibiotics and slow down the evolution of resistance to antibiotics. Our work provides a proof of principle for the development of peptide based antibiotic adjuvants that enhance antibiotic action and block evolution of resistance.
Project description:Bacterial evolution of antibiotic resistance frequently has deleterious side effects on microbial growth, virulence, and susceptibility to other antimicrobial agents. However, it is unclear how these trade-offs could be utilized for manipulating antibiotic resistance in the clinic, not least because the underlying molecular mechanisms are poorly understood. Using laboratory evolution, we demonstrate that clinically relevant resistance mutations in Escherichia coli constitutively rewire a large fraction of the transcriptome in a repeatable and stereotypic manner. Strikingly, lineages adapted to functionally distinct antibiotics and having no resistance mutations in common show a wide range of parallel gene expression changes that alter oxidative stress response, iron homeostasis, and the composition of the bacterial outer membrane and cell surface. These common physiological alterations are associated with changes in cell morphology and enhanced sensitivity to antimicrobial peptides. Finally, the constitutive transcriptomic changes induced by resistance mutations are largely distinct from those induced by antibiotic stresses in the wild-type. This indicates a limited role for genetic assimilation of the induced antibiotic stress response during resistance evolution. Our work suggests that diverse resistance mutations converge on similar global transcriptomic states that shape genetic susceptibility to antimicrobial compounds.
Project description:We report identification and characterization of antibiotic persister mutants carrying characteristic mutations in the Escherichia coli rpoB gene
Project description:Evolution of antibiotic resistance in microbes is frequently achieved by acquisition of spontaneous mutations during antimicrobial therapy. Here we demonstrate that inactivation of a central regulator of iron homeostasis (fur) facilitates laboratory evolution of ciprofloxacin resistance in Escherichia coli. To decipher the underlying molecular mechanisms, we first performed a global transcriptome analysis and demonstrated a substantial reorganization of the Fur regulon in response to antibiotic treatment. We hypothesized that the impact of Fur on evolvability under antibiotic pressure is due to the elevated intracellular concentration of free iron and the consequent enhancement of oxidative damage-induced mutagenesis. In agreement with expectations, over-expression of iron storage proteins, inhibition of iron transport, or anaerobic conditions drastically suppressed the evolution of resistance, while inhibition of the SOS response-mediated mutagenesis had no such effect in fur deficient population. In sum, our work revealed the central role of iron metabolism in de novo evolution of antibiotic resistance, a pattern that could influence the development of novel antimicrobial strategies. We used microarrays to identify genotype specific transcriptional changes under severe DNA damaging conditions (antibiotic ciprofloxacin). We treated Escherichia coli cells with a highly toxic level of ciprofloxacin (gyrase inhibitor) for RNA extraction and hybridization on Affymetrix microarrays. We planned to find genotype specific transcriptional responses using WT control (BW25113) and fur-knockout mutant (selected from the KEIO collection) strains during antibiotic treatments. For each treatment type we used two biological replicates.
Project description:Evolution of antibiotic resistance in microbes is frequently achieved by acquisition of spontaneous mutations during antimicrobial therapy. Here we demonstrate that inactivation of a central regulator of iron homeostasis (fur) facilitates laboratory evolution of ciprofloxacin resistance in Escherichia coli. To decipher the underlying molecular mechanisms, we first performed a global transcriptome analysis and demonstrated a substantial reorganization of the Fur regulon in response to antibiotic treatment. We hypothesized that the impact of Fur on evolvability under antibiotic pressure is due to the elevated intracellular concentration of free iron and the consequent enhancement of oxidative damage-induced mutagenesis. In agreement with expectations, over-expression of iron storage proteins, inhibition of iron transport, or anaerobic conditions drastically suppressed the evolution of resistance, while inhibition of the SOS response-mediated mutagenesis had no such effect in fur deficient population. In sum, our work revealed the central role of iron metabolism in de novo evolution of antibiotic resistance, a pattern that could influence the development of novel antimicrobial strategies. We used microarrays to identify genotype specific transcriptional changes under severe DNA damaging conditions (antibiotic ciprofloxacin).