Trifluoroacetic Acid as a Molecular Probe for the Dense Phase in Liquid-Liquid Phase-Separating Peptide Systems.

Although trifluoroacetic acid (TFA) is not typically considered a Hofmeister reagent, it has been demonstrated to modulate biocoacervation. We show that TFA can be employed to probe specific interactions in coacervating bioinspired peptide phenylalanine (Phe) F-labeled at a single site, altering its liquid-liquid phase separation (LLPS) behavior. Solid-state nuclear magnetic resonance (NMR) spectroscopy revealed two dynamically distinct binding modes of TFA with Phe, resulting in a structured, dipolar-ordered complex and a more dynamic complex, highlighting the proximity between TFA and Phe.

Prediction of conformational states in a coronavirus channel using Alphafold-2 and DeepMSA2: Strengths and limitations.

The envelope (E) protein is present in all coronavirus genera. This protein can form pentameric oligomers with ion channel activity which have been proposed as a possible therapeutic target. However, high resolution structures of E channels are limited to those of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), responsible for the recent COVID-19 pandemic.

Compliant Clients: Catechols Exhibit Enhanced Solubility and Stability in Diverse Complex Coacervates.

Polyelectrolyte coacervates, with their greater-than-water density, low interfacial energy, shear thinning viscosity, and ability to undergo structural arrest, mediate the formation of diverse load-bearing macromolecular materials in living organisms as well as in industrial material fabrication. Coacervates, however, have other useful attributes that are challenging to study given the metastability of coacervate colloidal droplets and a lack of suitable analytical methods. We adopt solution electrochemistry and nuclear magnetic resonance measurements to obtain remarkable insights about coacervates as solvent media for low-molecular-weight catechols.

Release of frustration drives corneal amyloid disaggregation by brain chaperone.

TGFBI-related corneal dystrophy (CD) is characterized by the accumulation of insoluble protein deposits in the corneal tissues, eventually leading to progressive corneal opacity. Here we show that ATP-independent amyloid-β chaperone L-PGDS can effectively disaggregate corneal amyloids in surgically excised human cornea of TGFBI-CD patients and release trapped amyloid hallmark proteins. Since the mechanism of amyloid disassembly by ATP-independent chaperones is unknown, we reconstructed atomic models of the amyloids self-assembled from TGFBIp-derived peptides and their complex with L-PGDS using cryo-EM and NMR.

Complete Sequences of the Velvet Worm Slime Proteins Reveal that Slime Formation is Enabled by Disulfide Bonds and Intrinsically Disordered Regions.

The slime of velvet worms (Onychophora) is a strong and fully biodegradable protein material, which upon ejection undergoes a fast liquid-to-solid transition to ensnare prey. However, the molecular mechanisms of slime self-assembly are still not well understood, notably because the primary structures of slime proteins are yet unknown. Combining transcriptomic and proteomic studies, the authors have obtained the complete primary sequences of slime proteins and identified key features for slime self-assembly.