Physiological adaptation in flagellar architecture improves chemotaxis in complex environments.

Bacteria navigate natural habitats with a wide range of mechanical properties, from the ocean to the digestive tract and soil, by rotating helical flagella like propellers. Species differ in the number, position, and shape of their flagella, but the adaptive value of these flagellar architectures is unclear. Many species traverse multiple types of environments, such as pathogens inside and outside a host.

Eukaryotic catecholamine hormones influence the chemotactic control of by binding to the coupling protein CheW.

SignificanceHost-emitted stress hormones significantly influence the growth and behavior of various bacterial species; however, their cellular targets have so far remained elusive. Here, we used customized probes and quantitative proteomics to identify the target of epinephrine and the α-adrenoceptor agonist phenylephrine in live cells of the aquatic pathogen . Consequently, we have discovered the coupling protein CheW, which is in the center of the chemotaxis signaling network, as a target of both molecules.

Vibrio cholerae Motility in Aquatic and Mucus-Mimicking Environments.

Cholera disease is caused by Vibrio cholerae infecting the lining of the small intestine and results in severe diarrhea. V. cholerae's swimming motility is known to play a crucial role in pathogenicity and may aid the bacteria in crossing the intestinal mucus barrier to reach sites of infection, but the exact mechanisms are unknown.

A multiscale 3D chemotaxis assay reveals bacterial navigation mechanisms.

How motile bacteria navigate environmental chemical gradients has implications ranging from health to climate science, but the underlying behavioral mechanisms are unknown for most species. The well-studied navigation strategy of Escherichia coli forms a powerful paradigm that is widely assumed to translate to other bacterial species. This assumption is rarely tested because of a lack of techniques capable of bridging scales from individual navigation behavior to the resulting population-level chemotactic performance.

More than propellers: how flagella shape bacterial motility behaviors.

Bacteria use a wide variety of flagellar architectures to navigate their environment. While the iconic run-tumble motility strategy of the peritrichously flagellated Escherichia coli has been well studied, recent work has revealed a variety of new motility behaviors that can be achieved with different flagellar architectures, such as single, bundled, or opposing polar flagella. The recent discovery of various flagellar gymnastics such as flicking and flagellar wrapping is increasingly shifting the view from flagella as passive propellers to versatile appendages that can be used in a wide range of conformations.

Monitoring the molecular composition of live cells exposed to electric pulses via label-free optical methods.

The permeabilization of the live cells membrane by the delivery of electric pulses has fundamental interest in medicine, in particular in tumors treatment by electrochemotherapy. Since underlying mechanisms are still not fully understood, we studied the impact of electric pulses on the biochemical composition of live cells thanks to label-free optical methods: confocal Raman microspectroscopy and terahertz microscopy. A dose effect was observed after cells exposure to different field intensities and a major impact on cell peptide/protein content was found.

Relative Contributions of Core Protein and Solvation Shell in the Terahertz Dielectric Properties of Protein Solutions.

The properties of the solvation shell surrounding biomolecules in a solution are fundamental to understand the modifications in the dynamics of the water molecules by peptides and proteins. The dynamics of the hydrogen bonding network typically occurs at the picosecond time scale, so terahertz spectroscopy is a unique tool to investigate the solvation shell. Here, we present the terahertz measurements of the refractive index and extinction coefficient of solutions of biomolecules of various molecular weights.