Interdisciplinary Nanoscience Centre (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark.
Published: August 2021
AI Article Synopsis
Article Abstract
Functional amyloids are highly organized protein/peptide structures that promote biofilm formation in different bacteria. One such example is provided by a family of 20-45 residue-long peptides called phenol-soluble modulins (PSMs) from . External components such as eukaryotic host proteins, which alter self-assembly of bacterial amyloids, can affect the biofilm matrix. Here, we studied the effect of the highly prevalent human plasma protein fibrinogen (Fg) on fibrillation of PSMs. Fg inhibits or suppresses fibrillation of most PSMs tested (PSMα1, PSMβ1, and PSMβ2) except for PSMα3, whose already rapid aggregation is accelerated even further by Fg but leads to amorphous β-rich aggregates rather than fibrils. Fg also induces PSMβ2 to form amorphous aggregates and diverts PSMα1 into off-pathway oligomers which consist of both Fg and PSMα1 and cannot seed fibrillation. Peptide arrays showed that Fg bound to the N-terminus of PSMα1, while it bound to the entire length of PSMα3 (except the C terminus) and to the C-termini of PSMβ1 and PSMβ2. The latter peptides are all positively charged, while Fg is negatively charged at physiological pH. The positive charges complement Fg's net negative charge of -7.6 at pH 7.4. Fg's ability to inhibit PSM fibrillation reveals a potential host-defense mechanism to prevent bacterial biofilm growth and infections in the human body.
Mas-related G protein-coupled receptor b2 (Mrgprb2) binding to its cationic endogenous and exogenous ligands induces mast cell degranulation and promotes inflammation in mice. However, the physiological roles of its human homologue MRGPRX2 remain unclear. Here we aimed to elucidate the mechanisms by which MRGPRX2 regulates vascular permeability, and generated MRGPRX2 knock-in (MRGPRX2-KI) and Mrgprb2 knockout (Mrgprb2-KO) mice.
Parkinson's Disease (PD) is a prevalent and escalating neurodegenerative disorder with significant societal implications. Despite being considered a proteinopathy, in which the aggregation of α-synuclein is the main pathological change, the intricacies of PD initiation remain elusive. Recent evidence suggests a potential link between gut microbiota and PD initiation, emphasizing the need to explore the effects of microbiota-derived molecules on neuronal cells.
Background: is an important conditionally pathogenic bacterium. SarZ, belonging to the SarA family protein, has been demonstrated in to promote the expression of invasive virulence factors while inhibiting biofilm formation. However, the regulatory role of SarZ on virulence is not completely understood.
In chronic rhinosinusitis (CRS), a shift in microbial populations leads to increased harmful bacteria and decreased beneficial ones, contributing to inflammation and disease severity.
The study identifies a specific secreted protein, δ-toxin, from a common URT pathogen that inhibits the aggregation and adherence of beneficial bacteria, disrupting their ability to coexist in the nasal environment.
These findings reveal a new mechanism by which pathogenic bacteria can outcompete commensal microbes, furthering the understanding of microbial dysbiosis in CRS and its implications for disease outcomes.
() is a prominent Gram-positive bacterial pathogen that expresses numerous cytotoxins known to target human polymorphonuclear leukocytes (PMNs or neutrophils). These include leukocidin G/H (LukGH, also known as LukAB), the Panton-Valentine leukocidin (PVL), γ-hemolysin A/B (HlgAB), γ-hemolysin B/C (HlgBC), leukocidin E/D (LukED), α-hemolysin (Hla), and the phenol-soluble modulin-α peptides (PSMα). However, the relative contribution of each of these cytotoxins in causing human PMN lysis is not clear.
