Preparing for the KIL: Receptor Analysis of Pseudomonas syringae pv. porri Phages and Their Impact on Bacterial Virulence.

The prevalence of Pseudomonas syringae pv. porri (Pspo) in Belgium continues to increase and sustainable treatments for this pathogen remain unavailable. A potentially attractive biocontrol strategy would be the application of bacteriophages. The ideal application strategy of phages in an agricultural setting remains unclear, especially in a field-based production such as for leek plants in Flanders. Therefore, more insight in bacteria-phage interaction is required, along with the evaluation of different application strategies. In this study, we further characterized the infection strategy of two Pspo phages, KIL3b and KIL5. We found that both phages recognize lipopolysaccharide (LPS) moieties on the surface of the bacterium. LPS is an important pathogenicity factor of Pspo. Our data also suggest that KIL5 requires an additional protein in the bacterial cytoplasmatic membrane to efficiently infect its host. Virulence tests showed that this protein also contributes to Pspo virulence. Furthermore, a cocktail of both phages was applied in a seed bioassay. A combination of KIL3b and KIL5 reduced the bacterial concentration 100-fold. However, in vitro Pspo resistance against phage infection developed quite rapidly. However, the impact of this phage resistance might be mitigated as is suggested by the fact that those resistance mutations preferably occur in genes involved in LPS metabolism, and that the virulence of those mutants is possibly reduced. Our data suggest that the phage cocktail has promising potential to lower the prevalence of Pspo and to be integrated in a pest management strategy. Targeted research is needed to further explore the applicability of the phages in combination with other disease control strategies.

Pharmacological modulation of septins restores calcium homeostasis and is neuroprotective in models of Alzheimer's disease.

Abnormal calcium signaling is a central pathological component of Alzheimer's disease (AD). Here, we describe the identification of a class of compounds called ReS19-T, which are able to restore calcium homeostasis in cell-based models of tau pathology. Aberrant tau accumulation leads to uncontrolled activation of store-operated calcium channels (SOCCs) by remodeling septin filaments at the cell cortex. Binding of ReS19-T to septins restores filament assembly in the disease state and restrains calcium entry through SOCCs. In amyloid-ß and tau-driven mouse models of disease, ReS19-T agents restored synaptic plasticity, normalized brain network activity, and attenuated the development of both amyloid-ß and tau pathology. Our findings identify the septin cytoskeleton as a potential therapeutic target for the development of disease-modifying AD treatments.