Escherichia coli
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ABSTRACT:
PROVIDER: PRJNA342154 | ENA |
REPOSITORIES: ENA
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Project description:We report the context-specific activity of two peptidyl transferase targeting antibiotics, chloramphenicol and linezolid. By generating ribosome profiling data in the presence or absence of either chloramphenicol or linezolid we mapped the relative change of ribosome density induced by these antibiotics. We find that both inhibitors preferentially arrest ribosomes that carry either an alanine, serine, or threonine in the penultimate (-1) position of the nascent peptide chain. Additionally ribosomes that carry a glycine in either the P site (0) or A-site (+1) counteract the inhibitory activity of both inhibitors. The context-specific action of chloramphenicol illuminates the operation of the mechanism of inducible resistance that relies on programmed drug-induced translation arrest. In addition, our findings expose the functional interplay between the nascent chain and the peptidyl transferase center.
2016-09-08 | GSE86536 | GEO
Project description:Macrolides are clinically important antibiotics thought to inhibit bacterial growth by impeding the passage of newly synthesized polypeptides through the nascent peptide exit tunnel of the bacterial ribosome. Recent data challenged this view by showing that macrolide antibiotics can differentially affect synthesis of individual proteins. In order to understand the general mechanism of macrolide action, we used genome-wide ribosome profiling and analyzed the redistribution of ribosomes translating highly expressed genes in bacterial cells treated with high concentrations of macrolide antibiotics. The metagene analysis indicated that inhibition of early rounds of translation, which would be characteristic of the conventional view of macrolide action, occurs only at a limited number of genes. Translation of most genes proceeds past the 5' proximal codons and can be arrested at more distal codons when the ribosome encounters specific short sequence motifs. The sequence motifs enriched in the sites of arrest are confined to the nascent peptide residues in the peptidyl transferase center but not to the peptide segments that contact the antibiotic molecule in the exit tunnel. This led to the conclusion that the general mode of macrolide action involves selective inhibition of peptide bond formation between specific combinations of donor and acceptor substrates. Additional factors operating in the living cell but not during in vitro protein synthesis may modulate site-specific action of macrolide antibiotics. Comparing ribosome distribution in bacterial cells treated with macrolide antibiotics against the control cells.
2014-11-03 | E-GEOD-61619 | biostudies-arrayexpress
Project description:Macrolides are clinically important antibiotics thought to inhibit bacterial growth by impeding the passage of newly synthesized polypeptides through the nascent peptide exit tunnel of the bacterial ribosome. Recent data challenged this view by showing that macrolide antibiotics can differentially affect synthesis of individual proteins. In order to understand the general mechanism of macrolide action, we used genome-wide ribosome profiling and analyzed the redistribution of ribosomes translating highly expressed genes in bacterial cells treated with high concentrations of macrolide antibiotics. The metagene analysis indicated that inhibition of early rounds of translation, which would be characteristic of the conventional view of macrolide action, occurs only at a limited number of genes. Translation of most genes proceeds past the 5' proximal codons and can be arrested at more distal codons when the ribosome encounters specific short sequence motifs. The sequence motifs enriched in the sites of arrest are confined to the nascent peptide residues in the peptidyl transferase center but not to the peptide segments that contact the antibiotic molecule in the exit tunnel. This led to the conclusion that the general mode of macrolide action involves selective inhibition of peptide bond formation between specific combinations of donor and acceptor substrates. Additional factors operating in the living cell but not during in vitro protein synthesis may modulate site-specific action of macrolide antibiotics.
2014-11-03 | GSE61619 | GEO
Project description:Antibiotics of the orthosomycin class bind at a distinct site on the large subunit of the bacterial ribosome not used by any other known protein synthesis inhibitor. Structural and biochemical in vitro studies suggested that orthosomycins should block accommodation of aminoacyl-tRNAs in the ribosomal A-site arresting the ribosome at the start codons of the genes. However, the mode of action of orthosomycins in the living cell remains unknown. Here, to get a general and unbiased view of the mode of action of orthosomycin antibiotics, we carried out genome-wide ribosome profiling analysis in Escherichia coli cells exposed to evernimicin, one of the most active antibiotics of this class. Our in vivo data, supported by the analysis of evernimicin action upon in vitro translation of a variety of mRNAs, argue that orthosomycins preferentially inhibit translation elongation and act in a context specific manner. We show that evernimicin predominantly arrests translation when the ribosome needs to accommodate Pro-tRNA or Leu-tRNA in the A site while polymerizing specific amino acid sequences. We further show that the discovered context specificity of orthosomycins is exploited for the programmed translation arrest that apparently regulates resistance to these antibiotics.
2022-04-15 | GSE193270 | GEO
Project description:The general mode of translation inhibition by macrolide antibiotics
| PRJNA261698 | ENA
Project description:Kasugamycin (KSG) is an aminoglycoside antibiotic widely used in agriculture and exhibiting considerable medical potential. Previous studies suggested that KSG interferes with translation by blocking binding of canonical mRNA and initiator tRNA to the small ribosomal subunit thereby preventing initiation of protein synthesis. Here, by using genome-wide approaches, we show that KSG can interfere with translation even after the formation of the 70S initiation complex on mRNA, as the extent of KSG-mediated translation inhibition correlates with increased occupancy of start codons by 70S ribosomes. We also show that KSG inhibits protein synthesis in a gene- and context-specific manner as even saturating concentrations of KSG do not completely abolish translation of all Escherichia coli genes. Differential action of KSG significantly depends on the nature of the mRNA residue immediately preceding the start codon, with guanine in this position being the most conducive to inhibition by the drug. In addition, the activity of KSG is attenuated by translational coupling as genes whose start codons overlap with the coding regions or the stop codons of the upstream cistrons tend to be less susceptible to drug-mediated inhibition. Altogether, our findings reveal KSG as the first example of a small ribosomal subunit-targeting antibiotic with a well-pronounced context specificity of action.
2022-02-02 | GSE185757 | GEO
Project description:Reducing protein synthesis slows growth and development but can increase adult lifespan. We demonstrate that knock-down of eukaryotic translation initiation factor 4G (eIF4G), which is down-regulated during starvation, results in differential translation of genes important for growth and longevity in C. elegans. Genome-wide mRNA translation state analysis showed that inhibition of IFG-1, the C. elegans ortholog of eIF4G, results in a relative increase in ribosomal loading and translation of stress response genes. Some of these genes are required for lifespan extension when IFG-1 is inhibited and are new determinants of longevity. Furthermore, enhanced ribosomal loading of certain mRNAs upon IFG-1 inhibition was correlated with increased mRNA length. This association was supported by changes in the proteome assayed via quantitative mass spectrometry. Our results support a role for IFG-1 in mediating the antagonistic effects on growth and somatic maintenance by modulating translation of a specific class of mRNA based on transcript length. 24 experimental samples were analyzed using custom oligo microarrays. A wild type sample pool was used as the Cy3 reference/control for all experimetal samples. All extracted RNA prior to array analysis was fractioned (via a sucrose gradient) based on ribosomal loading and pooled into ribosomal and free RNA (Fraction1), light polysomes (Fraction2) and heavy polysomes (Fraction3) as described in the experimental procedures. The control RNAi is ‘empty’ vector L4440 RNAi feeding vector plasmid (1999 Firelab vector kit) transformed HT115(DE3), which was obtained from the Caenorhabditis Genetics Center (University of Wisconsin).
2011-04-16 | E-GEOD-28665 | biostudies-arrayexpress
Project description:Ribosomal RNA modifications are introduced by specific enzymes during ribosome assembly in bacteria. Deletion of individual modification enzymes has a minor effect on bacterial growth, ribosome biogenesis, and translation, which has complicated the definition of the function of the enzymes and their products. We have constructed an E. coli strain lacking 10 genes encoding enzymes that modify 23S rRNA around the peptidyl-transferase center. This strain exhibits severely compromised growth and ribosome assembly, especially at lower temperatures. Ribosomal protein composition of the mature 50S ribosomes and free 50S subunits was analyzed by SILAC based qMS approach. We have found that absence of 23S rRNA modifications around PTC does not affect significantly r-protein content of incompletely assembled 50S or mature 50S ribosomes.
2024-03-15 | PXD047588 | Pride
Project description:Ribosomal RNA modifications are introduced by specific enzymes during ribosome assembly in bacteria. Deletion of individual modification enzymes has a minor effect on bacterial growth, ribosome biogenesis, and translation, which has complicated the definition of the function of the enzymes and their products. We have constructed an E. coli strain lacking 10 genes encoding enzymes that modify 23S rRNA around the peptidyl-transferase center. This strain exhibits severely compromised growth and ribosome assembly, especially at lower temperatures. Ribosomal protein composition of the mature 50S ribosomes and free 50S subunits was analyzed by SILAC based qMS approach. We have found that absence of 23S rRNA modifications around PTC does not affect significantly r-protein content of incompletely assembled 50S or mature 50S ribosomes.
2024-03-15 | PXD047376 | Pride
Project description:PoxtA and OptrA are ATP binding cassette (ABC) proteins of the F subtype (ABCF) that confer resistance to oxazolidinone, such as linezolid, and phenicol antibiotics, such as chloramphenicol. PoxtA/OptrA are often encoded on mobile genetic elements, facilitating their rapid spread amongst Gram-positive bacteria. These target protection proteins are thought to confer resistance by binding to the ribosome and dislodging the antibiotics from their binding sites. However, a structural basis for their mechanism of action has been lacking. Here by investigating 5'P mRNA decay intermediates, that provide ribosome protection data, we show that PoxtA protects against Linezolid specific stalls. Furthermore, we present cryo-electron microscopy structures of PoxtA in complex with the Enterococcus faecalis 70S ribosome at 2.9–3.1 Å, as well as the complete E. faecalis 70S ribosome at 2.2–2.5 Å. The structures reveal that PoxtA binds within the ribosomal E-site with its antibiotic resistance domain (ARD) extending towards the peptidyltransferase center (PTC) on the large ribosomal subunit. At its closest point, the ARD of PoxtA is still located >15 Å from the linezolid and chloramphenicol binding sites, suggesting that drug release is elicited indirectly. Instead, we observe that the ARD of PoxtA perturbs the CCA-end of the P-site tRNA causing it to shift by ~4 Å out of the PTC, which correlates with a register shift of one amino acid for the attached nascent polypeptide chain. Given that linezolid and chloramphenicol are context-specific translation elongation inhibitors, we postulate that PoxtA/OptrA confer resistance to oxazolidinones and phenicols indirectly by perturbing the P-site tRNA and thereby altering the conformation of the attached nascent chain to disrupt the drug binding site.
2022-02-12 | GSE179348 | GEO