Lidor, O. | Search bioRxiv

bioRxiv2019

An endophytic bacteria (Pseudomonas aeruginosa) strain translocated and protected tomato (Solanum lycopersicum L.) plants from its parasitic weed Phelipanche aegyptiaca

Phelipanche aegyptiaca is an obligate holo-parasitic weed lacking a functional photosynthetic system, which subsists on roots of a wide range of host crops, causing severe losses in yield quality and quantity. The parasite and its host are connected through their vascular system, forming a unique ecological system that enables the exchange of various substances. In a previous study, it was suggested that endophytic bacteria, which naturally inhabit the internal tissues of plants, can also be transmitted from the parasitic weed to its host and vice versa. In the current study, we investigate the characteristics of a previously isolated Pseudomonas sp. PhelS10 strain, using both biochemical and molecular methods. Our results revealed that production of Pseudomonas aeruginosa quinolone signal (PQS) was 2.1 times higher than that of the standard Pseudomonas aeruginosa strain (PAO1), which contributed to a 22% higher biofilm formation capability. PhelS10 strain was detected in the xylem of tomato plants using FISH analysis. In addition, PhelS10 strain was found in the parasitic weeds inner tissues, confirming the hypothesis that endophytic bacteria traffic between the plant host and its parasitic weed.

microbiology↗

bioRxiv2018

Structural Insights into Curli Amyloid Fibrils suggest Repurposing Anti-amyloid Compounds as Anti-biofilm Agents

Curli amyloid fibrils secreted by Enterobacteriaceae mediate host cell adhesion and contribute to biofilm formation, thereby promoting bacterial resistance to environmental stressors. Here, we present crystal structures of amyloid-forming segments from the major curlin subunit, CsgA, revealing steric zipper fibrils of tightly mated {beta}-sheets, demonstrating a structural link between curli and human pathological amyloids. We propose that these cross-{beta} segments structure the highly robust curli amyloid core. D-enantiomeric peptides, originally developed to interfere with Alzheimers disease-associated Amyloid-{beta}, inhibited CsgA fibrillation and reduced biofilm formation in Salmonella typhimurium. Moreover, CsgA fibrils cross-seeded fibrillation of Amyloid-{beta}, providing further support for the proposed structural resemblance and potential for cross-species amyloid interactions. In this study, we provide structural insights into curli formation, offer a novel strategy for disrupting amyloid-structured biofilms, and hypothesize on the formation of self-propagating prion-like species originating from a microbial source that could influence neurodegenerative diseases.\n\nSignificanceAtomic resolution structural insights into the biofilm-associated curli amyloid fibril secreted by Enterobacteriaceae revealed elements of fibrillar architecture conserved between bacterial and human amyloids. This inspired us to repurpose anti-amyloid drugs designed to target human pathological amyloids as a novel class of anti-biofilm agents. Moreover, the results provide a molecular basis for understanding interspecies cross-seeding of amyloids through the generation of prion-like agents by molecular mimicry. This raises concerns regarding human exposure to exogenous sources of amyloids, such as contaminated food and amyloid-secreting microbes. Overall, we provide a novel framework for investigating interspecies amyloid interactions at the molecular level and offer novel insights into mechanisms which may underlie the evolutionary and etiological relationships between the human and microbial amylomes.

biochemistry↗