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815500.8775Gut bacteria enable prostate cancer growth. Testosterone-synthetizing gut bacteria drive resistance to therapy.202134618567
81410.8759Drown Them in Their Own Garbage: a New Strategy To Reverse Polymyxin Resistance? Purcell and colleagues offer new insights into a major mechanism of polymyxin resistance in Gram-negative bacteria (A. B. Purcell, B. J. Voss, and M. S. Trent, J Bacteriol 204:e00498-21, 2022, https://doi.org/10.1128/JB.00498-21). Inactivating a single lipid recycling enzyme causes accumulation of waste lipid by-products that inhibit a key factor responsible for polymyxin resistance.202234843378
512020.8750ARIBA: rapid antimicrobial resistance genotyping directly from sequencing reads. Antimicrobial resistance (AMR) is one of the major threats to human and animal health worldwide, yet few high-throughput tools exist to analyse and predict the resistance of a bacterial isolate from sequencing data. Here we present a new tool, ARIBA, that identifies AMR-associated genes and single nucleotide polymorphisms directly from short reads, and generates detailed and customizable output. The accuracy and advantages of ARIBA over other tools are demonstrated on three datasets from Gram-positive and Gram-negative bacteria, with ARIBA outperforming existing methods.201729177089
10230.8740Paradoxical behaviour of pKM101; inhibition of uvr-independent crosslink repair in Escherichia coli by muc gene products. In strains of Escherichia coli deficient in excision repair (uvrA or uvrB), plasmid pKM101 muc+ but not pGW219 mucB::Tn5 enhanced resistance to angelicin monoadducts but reduced resistance to 8-methoxy-psoralen interstrand DNA crosslinks. Thermally induced recA-441 (= tif-1) bacteria showed an additional resistance to crosslinks that was blocked by pKM101. Plasmid-borne muc+ genes also conferred some additional sensitivity to gamma-radiation and it is suggested that a repair step susceptible to inhibition by muc+ gene products and possibly involving double-strand breaks may be involved after both ionizing radiation damage and psoralen crosslinks.19853883148
922640.8736Sequence-specific antimicrobials using efficiently delivered RNA-guided nucleases. Current antibiotics tend to be broad spectrum, leading to indiscriminate killing of commensal bacteria and accelerated evolution of drug resistance. Here, we use CRISPR-Cas technology to create antimicrobials whose spectrum of activity is chosen by design. RNA-guided nucleases (RGNs) targeting specific DNA sequences are delivered efficiently to microbial populations using bacteriophage or bacteria carrying plasmids transmissible by conjugation. The DNA targets of RGNs can be undesirable genes or polymorphisms, including antibiotic resistance and virulence determinants in carbapenem-resistant Enterobacteriaceae and enterohemorrhagic Escherichia coli. Delivery of RGNs significantly improves survival in a Galleria mellonella infection model. We also show that RGNs enable modulation of complex bacterial populations by selective knockdown of targeted strains based on genetic signatures. RGNs constitute a class of highly discriminatory, customizable antimicrobials that enact selective pressure at the DNA level to reduce the prevalence of undesired genes, minimize off-target effects and enable programmable remodeling of microbiota.201425240928
82250.8727Exoglucanase-encoding genes from three Wickerhamomyces anomalus killer strains isolated from olive brine. Wickerhamomyces anomalus killer strains are important for fighting pathogenic yeasts and for controlling harmful yeasts and bacteria in the food industry. Targeted disruption of key genes in β-glucan synthesis of a sensitive Saccharomyces cerevisiae strain conferred resistance to the toxins of W. anomalus strains BS91, BCA15 and BCU24 isolated from olive brine. Competitive inhibition of the killing activities by laminarin and pustulan refer to β-1,3- and β-1,6-glucans as the main primary toxin targets. The extracellular exoglucanase-encoding genes WaEXG1 and WaEXG2 from the three strains were sequenced and were found to display noticeable similarities to those from known potent W. anomalus killer strains.201323148020
998460.8718Multiplex base editing to convert TAG into TAA codons in the human genome. Whole-genome recoding has been shown to enable nonstandard amino acids, biocontainment and viral resistance in bacteria. Here we take the first steps to extend this to human cells demonstrating exceptional base editing to convert TAG to TAA for 33 essential genes via a single transfection, and examine base-editing genome-wide (observing ~40 C-to-T off-target events in essential gene exons). We also introduce GRIT, a computational tool for recoding. This demonstrates the feasibility of recoding, and highly multiplex editing in mammalian cells.202235918324
50770.8714Tellurite resistance and reduction by obligately aerobic photosynthetic bacteria. Seven species of obligately aerobic photosynthetic bacteria of the genera Erythromicrobium, Erythrobacter, and Roseococcus demonstrated high-level resistance to tellurite and accumulation of metallic tellurium crystals. High-level resistance without tellurite reduction was observed for Roseococcus thiosulfatophilus and Erythromicrobium ezovicum grown with certain organic carbon sources, implying that tellurite reduction is not essential to confer tellurite resistance.199616535446
818380.8710Modification of arthropod vector competence via symbiotic bacteria. Some of the world's most devastating diseases are transmitted by arthropod vectors. Attempts to control these arthropods are currently being challenged by the widespread appearance of insecticide resistance. It is therefore desirable to develop alternative strategies to complement existing methods of vector control. In this review, Charles Beard, Scott O'Neill, Robert Tesh, Frank Richards and Serap Aksoy present an approach for introducing foreign genes into insects in order to confer refractoriness to vector populations, ie. the inability to transmit disease-causing agents. This approach aims to express foreign anti-parasitic or anti-viral gene products in symbiotic bacteria harbored by insects. The potential use of naturally occurring symbiont-based mechanisms in the spread of such refractory phenotypes is also discussed.199315463748
998190.8709High-contrast imaging of cellular non-repetitive drug-resistant genes via in situ dead Cas12a-labeled PCR. In situ imaging of genes of pathogenic bacteria can profile cellular heterogeneity, such as the emergence of drug resistance. Fluorescence in situ hybridization (FISH) serves as a classic approach to image mRNAs inside cells, but it remains challenging to elucidate genomic DNAs and relies on multiple fluorescently labeled probes. Herein, we present a dead Cas12a (dCas12a)-labeled polymerase chain reaction (CasPCR) assay for high-contrast imaging of cellular drug-resistant genes. We employed a syncretic dCas12a-green fluorescent protein (dCas12a-GFP) to tag the amplicons, thereby enabling high-contrast imaging and avoiding multiple fluorescently labeled probes. The CasPCR assay can quantify quinolone-resistant Salmonella enterica in mixed populations and identify them isolated from poultry farms.202439229640
9784100.8695Antibiotic Resistance in Gram-Negative Bacteria: The Threat from the Pink Corner. Antibiotic resistance in Gram-negative bacteria is a formidable challenge in modern medicine [...].202439338287
9995110.8694Direct fluorescence in situ hybridization (FISH) in Escherichia coli with a target-specific quantum dot-based molecular beacon. Quantum dots (QDs) are inorganic fluorescent nanocrystals with excellent properties such as tunable emission spectra and photo-bleaching resistance compared with organic dyes, which make them appropriate for applications in molecular beacons. In this work, quantum dot-based molecular beacons (QD-based MBs) were fabricated to specifically detect β-lactamase genes located in pUC18 which were responsible for antibiotic resistance in bacteria Escherichia coli (E. coli) DH5α. QD-based MBs were constructed by conjugating mercaptoacetic acid-quantum dots (MAA-QDs) with black hole quencher 2 (BHQ2) labeled thiol DNA vial metal-thiol bonds. Two types of molecular beacons, double-strands beacons and hairpin beacons, were observed in product characterization by gel electrophoresis. Using QD-based MBs, one-step FISH in tiny bacteria DH5α was realized for the first time. QD-based MBs retained their bioactivity when hybridizing with complementary target DNA, which showed excellent advantages of eliminating background noise caused by adsorption of non-specific bioprobes and achieving clearer focus of genes in plasmids pUC18, and capability of bacterial cell penetration and signal specificity in one-step in situ hybridization.201020729070
9991120.8693A bifunctional dihydrofolate synthetase--folylpolyglutamate synthetase in Plasmodium falciparum identified by functional complementation in yeast and bacteria. Folate metabolism in the human malaria parasite Plasmodium falciparum is an essential activity for cell growth and replication, and the target of an important class of therapeutic agents in widespread use. However, resistance to antifolate drugs is a major health problem in the developing world. To date, only two activities in this complex pathway have been targeted by antimalarials. To more fully understand the mechanisms of antifolate resistance and to identify promising targets for new chemotherapies, we have cloned genes encoding as yet uncharacterised enzymes in this pathway. By means of complementation experiments using 1-carbon metabolism mutants of both Escherichia coli and Saccharomyces cerevisiae, we demonstrate here that one of these parasite genes encodes both dihydrofolate synthetase (DHFS) and folylpolyglutamate synthetase (FPGS) activities, which catalyse the synthesis and polyglutamation of folate derivatives, respectively. The malaria parasite is the first known example of a eukaryote encoding both DHFS and FPGS activities in a single gene. DNA sequencing of this gene in antifolate-resistant strains of P. falciparum, as well as drug-inhibition assays performed on yeast and bacteria expressing PfDHFS--FPGS, indicate that current antifolate regimes do not target this enzyme. As PfDHFS--FPGS harbours two activities critical to folate metabolism, one of which has no human counterpart, this gene product offers a novel chemotherapeutic target with the potential to deliver a powerful blockage to parasite growth.200111223131
112130.8693Glycopeptide resistance determinants from the teicoplanin producer Actinoplanes teichomyceticus. In enterococci and other pathogenic bacteria, high-level resistance to vancomycin and other glycopeptide antibiotics requires the action of the van genes, which direct the synthesis of peptidoglycan terminating in the depsipeptide D-alanyl-D-lactate, in place of the usual D-Ala-D-Ala. The Actinoplanes teichomyceticus tcp cluster, devoted to the biosynthesis of the glycopeptide antibiotic teicoplanin, contains van genes associated to a murF-like sequence (murF2). We show that A. teichomyceticus contains also a house-keeping murF1 gene, capable of complementing a temperature sensitive Escherichia coli murF mutant. MurF1, expressed in Streptomyces lividans, can catalyze the addition of either D-Ala-D-Ala or D-Ala-D-Lac to the UDP-N-acetyl-muramyl-L-Ala-D-Glu-d-Lys. However, similarly expressed MurF2 shows a small enzymatic activity only with D-Ala-D-lactate. Introduction of a single copy of the entire set of van genes confers resistance to teicoplanin-type glycopeptides to S. coelicolor.200415500981
538140.8692The biochemical and genetic basis for high frequency thiomethyl galactoside resistance in lambda,lambdadg lysogens of Escherichia coli. In a culture of Escherichia coli K12 gal (lambdadg), cells which form large colonies on agar plates containing galactose and thiomethyl beta-D-galactoside (TMG) appear at high frequency. These clones are resistant to growth inhibition by TMG on galactose minimal medium. Biochemical studies of the steady-state levels of galactokinase and UDPgalactose 4-epimerase suggest that the resistant clones have extra copies of the genes for the galactose-metabolizing enzymes. The mutation for TMG resistance is not located in either the bacterial or the bacteriophage genome, but is probably due to an aberrant association between cell and prophage DNA. Mapping the TMG-resistant characteristic by phage P1 indicates that TMG-resistant bacteria posses at least two GAL+ OPERONS, ONE OF WHICH IS COTRANSDUCIBLe with bio+. In addition, TMG-resistant bacteria behave like lambdadg polylysogens when challenged with the phage lambdaI90c17. From these genetic experiments we conclude that TMG-resistant bacteria arise by duplication of the lambdadg prophage. Finally, gal+ bacteria which carry a single, additional, lambdadg prophage are TMG-resistant. TMG resistance is probably a gal+ gene dosage effect.1978344832
110150.8691Resistance to the macrolide antibiotic tylosin is conferred by single methylations at 23S rRNA nucleotides G748 and A2058 acting in synergy. The macrolide antibiotic tylosin has been used extensively in veterinary medicine and exerts potent antimicrobial activity against Gram-positive bacteria. Tylosin-synthesizing strains of the Gram-positive bacterium Streptomyces fradiae protect themselves from their own product by differential expression of four resistance determinants, tlrA, tlrB, tlrC, and tlrD. The tlrB and tlrD genes encode methyltransferases that add single methyl groups at 23S rRNA nucleotides G748 and A2058, respectively. Here we show that methylation by neither TlrB nor TlrD is sufficient on its own to give tylosin resistance, and resistance is conferred by the G748 and A2058 methylations acting together in synergy. This synergistic mechanism of resistance is specific for the macrolides tylosin and mycinamycin that possess sugars extending from the 5- and 14-positions of the macrolactone ring and is not observed for macrolides, such as carbomycin, spiramycin, and erythromycin, that have different constellations of sugars. The manner in which the G748 and A2058 methylations coincide with the glycosylation patterns of tylosin and mycinamycin reflects unambiguously how these macrolides fit into their binding site within the bacterial 50S ribosomal subunit.200212417742
8157160.8691Autologous DNA mobilization and multiplication expedite natural products discovery from bacteria. The transmission of antibiotic-resistance genes, comprising mobilization and relocation events, orchestrates the dissemination of antimicrobial resistance. Inspired by this evolutionarily successful paradigm, we developed ACTIMOT, a CRISPR-Cas9-based approach to unlock the vast chemical diversity concealed within bacterial genomes. ACTIMOT enables the efficient mobilization and relocation of large DNA fragments from the chromosome to replicative plasmids within the same bacterial cell. ACTIMOT circumvents the limitations of traditional molecular cloning methods involving handling and replicating large pieces of genomic DNA. Using ACTIMOT, we mobilized and activated four cryptic biosynthetic gene clusters from Streptomyces, leading to the discovery of 39 compounds across four distinct classes. This work highlights the potential of ACTIMOT for accelerating the exploration of biosynthetic pathways and the discovery of natural products.202439666857
8435170.8690Antimicrobial Zeolitic Imidazolate Frameworks with Dual Mechanisms of Action. The horizontal transfer of drug-resistant genes and the formation of biofilm barriers have threatened the therapeutic efficacy of conventional antibiotic drugs. Development of non-antibiotic agents with high delivery efficiency through bacterial biofilms is urgently required. A pyrithione (PT)-loading zeolitic imidazolate framework (ZIF-8@PT) is synthesized to destroy biofilms and improve the sensitivity of bacteria to PT. ZIF-8@PT can target and destroy the biofilm as well as the cell membrane, promoting the intracellular delivery of PT and possibly its interaction with SmpB, a protein that could regulate the drug resistance of bacteria. ZIF-8@PT effectively suppresses abdominal infections induced by multiresistant Aeromonas veronii C4 in rodent models without systemic toxicity. ZIF-8@PT promises wide applications in treating infections caused by multidrug-resistant bacteria through a dual mechanism of action.202336815744
823180.8687Characterization of the prtA and prtB genes of Erwinia chrysanthemi EC16. Two tandem metalloprotease-encoding structural genes, prtA and prtB, were sequenced from Erwinia chrysanthemi EC16. These were highly homologous to previously reported genes from the same bacteria, as well as to three other metalloprotease-encoding genes from enteric bacteria. The three tandem prt structural genes from strain EC16 were closely linked to a cluster of genes previously found to be essential for extracellular secretion of the metalloproteases.19938224883
558190.8686Thiamine pyrophosphate riboswitches are targets for the antimicrobial compound pyrithiamine. Thiamine metabolism genes are regulated in numerous bacteria by a riboswitch class that binds the coenzyme thiamine pyrophosphate (TPP). We demonstrate that the antimicrobial action of the thiamine analog pyrithiamine (PT) is mediated by interaction with TPP riboswitches in bacteria and fungi. For example, pyrithiamine pyrophosphate (PTPP) binds the TPP riboswitch controlling the tenA operon in Bacillus subtilis. Expression of a TPP riboswitch-regulated reporter gene is reduced in transgenic B. subtilis or Escherichia coli when grown in the presence of thiamine or PT, while mutant riboswitches in these organisms are unresponsive to these ligands. Bacteria selected for PT resistance bear specific mutations that disrupt ligand binding to TPP riboswitches and derepress certain TPP metabolic genes. Our findings demonstrate that riboswitches can serve as antimicrobial drug targets and expand our understanding of thiamine metabolism in bacteria.200516356850