Does the Hfq Protein Contribute to RNA Cargo Translocation into Bacterial Outer Membrane Vesicles?

Gram-negative bacteria release outer membrane vesicles (OMVs) that play a central role in host–pathogen interactions by transporting biomolecules, including proteins and nucleic acids. In this article, Marisela Velez and Véronique Arluison investigate the role of the RNA chaperone Hfq in mediating the interaction of small regulatory RNAs (sRNAs) with bacterial membranes.

In this article, it is shown that RNA binding to the inner membrane of Escherichia coli occurs in an Hfq-dependent manner. The study further demonstrates that membrane composition is a key factor in this process, with cardiolipin-rich lipid domains significantly enhancing RNA–membrane interactions. These findings provide new insight into the mechanism of RNA translocation from the cytoplasm to the periplasm, supporting its subsequent incorporation into OMVs.

Atomic force microscopy (AFM) was used to verify the formation and integrity of supported lipid bilayers and to monitor peptide–membrane interactions. Imaging was performed in tapping mode using a NanoWorld PNP-DB AFM probe with a resonance frequency of 15 kHz and a spring constant of 0.48 N/m. Measurements were carried out in liquid environment, enabling high-resolution characterization of biologically relevant membrane structures.

This work highlights the importance of AFM-based analysis for studying lipid–protein interactions and provides new understanding of RNA transport mechanisms in bacterial systems.

Figure 1
E. coli lipid bilayer incubated in the absence (A) or presence (B) of Hfq-CTR. Panel (A) shows the E. coli lipids bilayer. The height profile under the line shown on the upper image indicates that the domains are 0.8 nm higher than the rest of the membrane. The lower panel shows a three-dimensional representation of a small region. Panel (B) shows the E. coli lipid bilayer incubated in the presence of Hfq-CTR. The peptide accumulated on top of some of the domains, generating 1 nm high regions in some of them, as shown on the height profile. The arrows point the regions where the change in height occurs.

Full citation:
Velez, M.; Arluison, V.
Does the Hfq Protein Contribute to RNA Cargo Translocation into Bacterial Outer Membrane Vesicles?
Pathogens 2025, 14(4), 399.

https://doi.org/10.3390/pathogens14040399

License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

 

Fabrication of Thin-Film Composite Nanofiltration Membrane Employing Polyelectrolyte and Metal–Organic Framework (MOF) via Spin-Spray-Assisted Layer-by-Layer Assembly

Spin‑spray‑assisted layer‑by‑layer (LbL) assembly is an innovative technique for producing nanostructured thin films due to its rapid deposition and excellent substrate coverage. In this article, Farid Fadhillah fabricated a nanofiltration (NF) membrane composed of multilayers of polyethyleneimine (PEI) and poly(sodium‑4‑styrene sulfonate) (PSS) on a polysulfone (PSF) support. The resulting membrane was subsequently coated with a metal–organic framework (MOF303).
The fabricated (PEI/PSS)₅–MOF303 membrane demonstrated a rejection rate of 18.94 ± 1.58% and a permeability of 0.91 ± 0.13 L/(h·bar·m²), while also exhibiting improved antifouling performance. These findings highlight the potential of spin‑spray‑assisted LbL assembly as a promising route for thin‑film composite membrane fabrication.
Surface characterization was performed using a commercially available AFM system equipped with a NanoWorld Arrow‑CONTR AFM probe, a silicon cantilever with a force constant of 0.2 N/m, operated in contact mode. Lateral images were used to visualize surface inhomogeneities across the scanned region. The NanoWorld AFM probe ensured stable tip–sample interaction, enabling high‑quality topographical and lateral force mapping. This article emphasizes the importance of selecting a reliable AFM probe for nanoscale membrane characterization.

4. Atomic Force Microscope image ((left): lateral retrace (scan size 100 × 100 μm), (right): particle size (scan size: 10 × 10 μm)).
4. Atomic Force Microscope image ((left): lateral retrace (scan size 100 × 100 μm), (right): particle size (scan size: 10 × 10 μm)).

Full Citation:

Farid Fadhillah. Fabrication of Thin-Film Composite Nanofiltration Membrane Employing Polyelectrolyte and Metal–Organic Framework (MOF) via Spin-Spray-Assisted Layer-by-Layer Assembly. Engineering Proceedings, 2025, 105(1). DOI: https://doi.org/10.3390/engproc2025105003

Citing Licence

This article is published under the Creative Commons Attribution (CC BY) license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. © 2025 by the author. Published by MDPI.

Structural Elucidation of Citric Acid Cross-Linked Pectin and Its Impact on the Properties of Nanocellulose-Reinforced Packaging Films

Citric acid cross-linking is an effective strategy for modifying citrus pectin to enhance its performance in sustainable packaging applications. In this article, Chandra Mohan Chandrasekar, Daniele Carullo, Francesco Saitta, Tommaso Bellesia, Elena Caneva, Chiara Baschieri, Marco Signorelli, Dimitrios Fessas, Stefano Farris and Davide Romano, investigated the structural changes induced by citric acid cross-linking and their influence on the properties of nanocellulose-reinforced packaging films..

The authors demonstrated that cross-linking significantly alters the structure–property relationship of the biopolymer matrix, leading to improved film integrity and modified surface morphology. These results provide valuable insight into biopolymer modification strategies for the development of environmentally friendly packaging materials.

Atomic force microscopy (AFM) was employed to characterize the surface morphology of the films. Measurements were performed using a commercially available AFM instrument operated in contact resonance amplitude imaging (CRAI) mode. A NanoWorld Arrow-FMR AFM probe was used.

This AFM probe features a rectangular beam with a triangular free end and a tetrahedral tip (tip radius ~10 nm, tip height 10–15 μm), with a spring constant of 2.8 N/m and a resonance frequency of 75 kHz. Root mean square surface roughness values were calculated from at least five height-mode images.

Fig. 3. 2D synchronized correlation analysis of FTIR spectra for CLCP packaging film trials.
Fig. 3. 2D synchronized correlation analysis of FTIR spectra for CLCP packaging film trials. [The intensity of the auto-peaks on the diagonal line represents the overall change in spectral intensity. The key region of interest is the strong auto-peak around 1700 cm−1, highlighted by

Full citation: Chandrasekar, C. M.; Carullo, D.; Saitta, F.; Bellesia, T.; Caneva, E.; Baschieri, C.; Signorelli, M.; Fessas, D.; Farris, S.; Romano, D. “Structural elucidation of citric acid cross-linked pectin and its impact on the properties of nanocellulose-reinforced packaging films.” International Journal of Biological Macromolecules 2025, 333(2), 148869. https://doi.org/10.1016/j.ijbiomac.2025.148869

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