No abstract

AbstractBiomolecular condensates play a key role in organizing RNAs and proteins into membraneless organelles. Bacterial RNP-bodies (BR-bodies) are a biomolecular condensate containing the RNA degradosome mRNA decay machinery, but the biochemical function of such organization remains poorly defined. Here we define the RNA substrates of BR-bodies through enrichment of the bodies followed by RNA-seq. We find that long, poorly translated mRNAs, small RNAs, and antisense RNAs are the main substrates, while rRNA, tRNA, and other conserved ncRNAs are excluded from these bodies. BR-bodies stimulate the mRNA decay rate of enriched mRNAs, helping to reshape the cellular mRNA pool. We also observe that BR-body formation promotes complete mRNA decay, avoiding the build-up of toxic endo-cleaved mRNA decay intermediates. The combined selective permeability of BR-bodies for both, enzymes and substrates together with the stimulation of the sub-steps of mRNA decay provide an effective organization strategy for bacterial mRNA decay.

Chiroptical spectroscopies like circular dichroism report on the handedness of molecules but are often limited to the high-concentration regime because of the mismatch between the wavelength of propagating visible light and the size of molecules. Recent work has demonstrated that the electromagnetic fields generated near chiral plasmonic nanostructures can have high optical chirality that bridges these length scales and can induce high-fluorescence dissymmetry signals from achiral dyes by redirecting their emission. As a step toward single-molecule chiral sources, the induced fluorescence dissymmetry and apparent emission pattern near chiral plasmonic nanoparticles must be quantified. Here, we measure the induced fluorescence dissymmetry from the achiral dye Cy5.5 near a chiral gold nanodimer structure, and we map out the apparent emission pattern of the dyes using super-resolution single-molecule microscopy. Our high-sensitivity approach quantifies the fluorescence dissymmetry from sampling only ∼100 zeptomoles of Cy5.5 and measures from Cy5.5 near gold nanodimers median fluorescence dissymmetry factors that are 2 orders of magnitude greater than those of synthesized chiral fluorescent molecules. We observe a spatial correlation between the simulated optical chirality about a plasmonic gold nanodimer and experimentally obtained super-resolution apparent emission patterns, and we use the incident polarization to control our detection bias for the brightest molecules to sample nanometer-scale regions of high electric flux.

Chiral metasurface with orthogonal nanohelical metal arrays provide strong optical rotation but demands multi-step nanofabrication at low-pressure and/or high-temperature conditions, which is incompatible with many substrates and high-throughput assessment. Submillimeter local photonic patterns with various optical polarization were also hitherto unattainable over the same substrate. Here, we demonstrate direct substrate-tolerant printing of silver nanohelicoids with a locally variable optical activity using circularly polarized light (CPL), producing centimeter-scale chiral metasurface within minutes. The light-illuminated sites on the substrate immersed in an aqueous silver ion solution are activated for heterogeneous nucleation at room temperature. Subsequent CPL-induced asymmetric site-selective deposition and self-assembly of the silver nanoparticles (NPs) sculpt the orthogonal silver helicoids at the interface as one-pot synthesis. The ellipticity and wavelength of the incident photons control the handedness and size of the printed silver helicoids, realizing on-the-fly modulation of optical polarization while printing local patterns. Processing simplicity, high polarization rotation, and fine spatial resolution of the light-driven printing can provide a pathway to the sustainable production of chiral plasmonic metasurfaces, accelerating the development of chiral photonics for health and information technologies.