The Problem
True or False: There has been a surge of new antibiotic classes approved in the past 5-6 decades, especially against Gram-negative bacteria.
What is False? (There has been a concerning DEARTH of new approved antibiotic classes)
PIE stands for this—the class of polymers the authors synthesized.
What is Poly(Imidazolium Ester)?
This dye stains DNA only in cells with damaged membranes.
What is propidium iodide (PI)?
LLPS stands for this—the process by which P8 forms droplets with nucleic acids.
What is Liquid-Liquid Phase Separation?
P8 sequesters approximately this percentage of intracellular nucleic acids into condensates.
What is 74%?
This 2018 Lancet paper by Tacconelli et al. created a priority list of antibiotic-resistant bacteria that guided this study's focus.
What is the WHO Priority List of Antibiotic-Resistant Bacteria?
P8 was identified as the lead compound from a library of this many PIEs.
What is 15? (P1-P15)
The authors used this imaging technique to visualize bacterial ultrastructure and confirm membranes were intact.
What is Cryo-Electron Microscopy (Cryo-EM)?
P8 forms condensates with nucleic acids at concentrations as low as this for short dsDNA.
What is 2 μg/mL? (or 0.25 μg/mL for longer nucleic acids)
In vitro transcription was inhibited at P8 concentrations at or above this.
What is 4 μg/mL?
P8 has a molecular weight in this range, as determined by GPC.
What is 760-1081 Da?
This imaging technique with FITC-P8 showed the polymer progressively entering bacterial cytoplasm without letting PI in.
What is time-lapse confocal microscopy?
This technique measures molecular mobility within condensates by bleaching a region and watching recovery.
What is Fluorescence Recovery After Photobleaching (FRAP)?
P8 inhibits this process primarily, as shown by lower EC₅₀ with plasmid DNA vs. mRNA in CFPS.
What is transcription? (not translation)
These two last-resort antibiotics, one a carbapenem and one a polymyxin, are failing against resistant bacteria.
What are carbapenem and colistin?
The ester linkages in PIEs make them this—a property that prevents toxic accumulation in the body.
What is biodegradable?
Unlike most cationic antimicrobial polymers, P8 does this across the membrane rather than disrupting it.
What is translocate?
P8 binds DNA via these two modes, as shown by displacement of Hoechst 33342 and ethidium bromide.
What are minor groove binding and intercalation?
P8 clusters with this RNA synthesis inhibitor in PCA when analyzed by morphology and membrane markers.
What is rifampicin?
What does ESKAPE stand for?
What is Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp. ?
The authors changed the counterion in the final PIEs from Br⁻ to this, verified by X-ray photoelectron spectroscopy.
What is Cl⁻ (chloride)?
In mammalian cells (3T3 fibroblasts), P8 showed this compared to bacterial cells, explaining its selectivity.
What is minimal/limited membrane translocation (or lower accumulation)?
Adding KCl (disrupting this force) and urea (disrupting this force) destroyed condensates, but 1,6-hexanediol did not.
What are electrostatic interactions and hydrogen bonding? (Not hydrophobic)
BCP stands for this—a technique that uses fluorescence microscopy and PCA to infer antibiotic mechanism.
What is Bacterial Cytological Profiling?