Direct assessment in bacteria of prionoid propagation and phenotype selection by Hsp70 chaperone.

Protein amyloid aggregates epigenetically determine either advantageous or proteinopathic phenotypes. Prions are infectious amyloidogenic proteins, whereas prionoids lack infectivity but spread from mother to daughter cells. While prion amyloidosis has been studied in yeast and mammalian cells models, the dynamics of transmission of an amyloid proteinopathy has not been addressed yet in bacteria. Using time-lapse microscopy and a microfluidic set-up, we have assessed in Escherichia coli the vertical transmission of the amyloidosis caused by the synthetic bacterial model prionoid RepA-WH1 at single cell resolution within their lineage context. We identify in vivo the coexistence of two strain-like types of amyloid aggregates within a genetically identical population and a controlled homogeneous environment. The amyloids are either toxic globular particles or single comet-shaped aggregates that split during cytokinesis and exhibit milder toxicity. Both segregate and propagate in sublineages, yet show interconversion. ClpB (Hsp104) chaperone, key for spreading of yeast prions, has no effect on the dynamics of the two RepA-WH1 aggregates. However, the propagation of the comet-like species is DnaK (Hsp70)-dependent. The bacterial RepA-WH1 prionoid thus provides key qualitative and quantitative clues on the biology of intracellular amyloid proteinopathies.

A new F-box protein 7 gene mutation causing typical Parkinson's disease.

BACKGROUND: Recessive mutations in the F-box protein 7 gene (FBXO7; PARK15) have been identified as a cause of the parkinsonian-pyramidal syndrome. Here, we report clinical and genetic findings in a Turkish family with novel FBXO7 mutations. METHODS: Whole exome and targeted Sanger sequencing were performed for genetic analysis in a family with two members affected by Parkinson's disease (PD). All family members underwent detailed clinical, mental, and neurological examination. RESULTS: The new p.L34R (c.101 T>G) FBXO7 mutation was detected in a homozygous state in two Turkish sibs with typical levodopa-responsive PD. CONCLUSION: This is the first time a FBXO7 mutation has been identified that causes a phenotype compatible with typical idiopathic PD and presents with some of its common nonmotor features, such as rapid eye movement sleep behavior disorder, depression, and anxiety.

Localization of protein aggregation in Escherichia coli is governed by diffusion and nucleoid macromolecular crowding effect.

Aggregates of misfolded proteins are a hallmark of many age-related diseases. Recently, they have been linked to aging of Escherichia coli (E. coli) where protein aggregates accumulate at the old pole region of the aging bacterium. Because of the potential of E. coli as a model organism, elucidating aging and protein aggregation in this bacterium may pave the way to significant advances in our global understanding of aging. A first obstacle along this path is to decipher the mechanisms by which protein aggregates are targeted to specific intercellular locations. Here, using an integrated approach based on individual-based modeling, time-lapse fluorescence microscopy and automated image analysis, we show that the movement of aging-related protein aggregates in E. coli is purely diffusive (Brownian). Using single-particle tracking of protein aggregates in live E. coli cells, we estimated the average size and diffusion constant of the aggregates. Our results provide evidence that the aggregates passively diffuse within the cell, with diffusion constants that depend on their size in agreement with the Stokes-Einstein law. However, the aggregate displacements along the cell long axis are confined to a region that roughly corresponds to the nucleoid-free space in the cell pole, thus confirming the importance of increased macromolecular crowding in the nucleoids. We thus used 3D individual-based modeling to show that these three ingredients (diffusion, aggregation and diffusion hindrance in the nucleoids) are sufficient and necessary to reproduce the available experimental data on aggregate localization in the cells. Taken together, our results strongly support the hypothesis that the localization of aging-related protein aggregates in the poles of E. coli results from the coupling of passive diffusion-aggregation with spatially non-homogeneous macromolecular crowding. They further support the importance of "soft" intracellular structuring (based on macromolecular crowding) in diffusion-based protein localization in E. coli.

Bioinformatics-based discovery and identification of new biologically active peptides for GPCR deorphanization.

Owing to their involvement in many physiological and pathological processes, G-protein-coupled receptors (GPCRs) are interesting targets for drug development. Approximately, 100 endoGPCRs lack their natural ligands and remain orphan (oGPCRs). Consequently, oGPCR deorphanization appears a promising research field for the development of new therapeutics. On the basis of the knowledge of currently known GPCR/ligand couples, some oGPCRs may be targeted by peptides. However, to find new drugs for GPCRs, Genepep has developed a dedicated bioinformatics platform to screen transcriptomic databases for the prediction of new GPCR ligands. The peptide lists generated include specific data, such as chemical and physical properties, the occurrence of post-translational modifications (PTMs) and an annotation referring to the location and expression level of the related putative genes. This information system allows a selection through series of biological criteria of approximately 10 000 natural peptides including already known GPCR ligands and potential new candidates for GPCR deorphanization. The most promising peptides for functional assay screening and future development as therapeutic agents are under evaluation.