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 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.Comment: PLoS Computational Biology (2013

Dynamic of protein aggregation in Escherichia coli

L’agrégation protéique joue un rôle clé dans la dégénérescence cellulaire et est notamment reliée à de nombreuses maladies humaines en lien avec le vieillissement telles que les maladies d’Alzheimer et Parkinson ou encore la maladie du prion. Chez la bactérie Escherichia coli, l’accumulation de dommages sous forme d’agrégats protéiques et leur ségrégation asymétrique au pôle ont permis de démontrer des signes de vieillissement chez cette bactérie. Cette thèse s’est concentrée sur l’étude de la dynamique spatiale des agrégats protéiques in vivo chez la bactérie E. coli. Les agrégats protéiques peuvent être classifiés comme corps d’inclusion dont on dit souvent qu’ils sont amorphes ou comme amyloïdes dont le niveau de structuration est très élevée par la présence de nombreux feuillets β. Combinant une double approche théorique et expérimentale, basée sur la modélisation et la microscopie time-lapse et microfluidique, nous avons étudié le mécanisme gouvernant le mouvement des agrégats protéiques et la transmission verticale d’agrégats de type prionoide sur plusieurs dizaines de générations. Nos résultats indiquent clairement que les agrégats protéiques sont régis par un mouvement Brownien de diffusion avec un coefficient de diffusion dépendant de la taille de la molécule. L’étude de protéinopathie amyloïde a démontré l’existence de lignages propageant deux types d’agrégats : globulaire ou en forme de "comet-like". Les lignées présentant les agrégats sous forme globulaire indiquent une augmentation de la taille des agrégats jusqu’à inhibition de la division cellulaire tandis que la forme "comet-like" est moins préjudiciable à la croissance. Nous avons également observé à faible fréquence des lignées avec un changement de type d’agrégat. A partir d’un agrégat gobulaire, des agrégats "comet-like" peuvent naître.Protein aggregation plays a key role in cell decline and leads to several human disease linked to ageing like Alzheimer or Parkinson disease and prion disease. In Escherichia coli bacteria, ac- cumulation of damaged proteins and their asymmetric segregation allowed to show ageing signs. This thesis is focused on the in vivo spatial dynamics of protein aggregates in E. coli. Protein aggregates can be classified as inclusion bodies and they are amorphous or amyloid with a high order level due to β sheets. Combining a double theoretical and experimental approach, based on modeling and time-lapse and microfluidic microscopy, we studied the mechanism governing the motion of protein aggregates and the long-term vertical transmission of prionoid aggregates for about 10 generations. Our results show clearly that Brownian diffusion governs the motion of protein aggregates and the diffusion coefficient depends on the molecule size. The amyloid proteinopathy study shows the existence of lineages propagating two kind of aggregates : globular or comet-like. Lineages maintaining globular aggregates present an increase of the aggregate size until inhibition of the growth rate while comet-like aggregates are mildly detrimental to growth. We observed also at low frequency in some lineages the presence of both aggregates and a switch between them. Glo- bular foci give born to comet-like aggregates

Dynamique de l'agrégation protéique chez la bactérie Escherichia coli

Protein aggregation plays a key role in cell decline and leads to several human disease linked to ageing like Alzheimer or Parkinson disease and prion disease. In Escherichia coli bacteria, ac- cumulation of damaged proteins and their asymmetric segregation allowed to show ageing signs. This thesis is focused on the in vivo spatial dynamics of protein aggregates in E. coli. Protein aggregates can be classified as inclusion bodies and they are amorphous or amyloid with a high order level due to β sheets. Combining a double theoretical and experimental approach, based on modeling and time-lapse and microfluidic microscopy, we studied the mechanism governing the motion of protein aggregates and the long-term vertical transmission of prionoid aggregates for about 10 generations. Our results show clearly that Brownian diffusion governs the motion of protein aggregates and the diffusion coefficient depends on the molecule size. The amyloid proteinopathy study shows the existence of lineages propagating two kind of aggregates : globular or comet-like. Lineages maintaining globular aggregates present an increase of the aggregate size until inhibition of the growth rate while comet-like aggregates are mildly detrimental to growth. We observed also at low frequency in some lineages the presence of both aggregates and a switch between them. Glo- bular foci give born to comet-like aggregates.L’agrégation protéique joue un rôle clé dans la dégénérescence cellulaire et est notamment reliée à de nombreuses maladies humaines en lien avec le vieillissement telles que les maladies d’Alzheimer et Parkinson ou encore la maladie du prion. Chez la bactérie Escherichia coli, l’accumulation de dommages sous forme d’agrégats protéiques et leur ségrégation asymétrique au pôle ont permis de démontrer des signes de vieillissement chez cette bactérie. Cette thèse s’est concentrée sur l’étude de la dynamique spatiale des agrégats protéiques in vivo chez la bactérie E. coli. Les agrégats protéiques peuvent être classifiés comme corps d’inclusion dont on dit souvent qu’ils sont amorphes ou comme amyloïdes dont le niveau de structuration est très élevée par la présence de nombreux feuillets β. Combinant une double approche théorique et expérimentale, basée sur la modélisation et la microscopie time-lapse et microfluidique, nous avons étudié le mécanisme gouvernant le mouvement des agrégats protéiques et la transmission verticale d’agrégats de type prionoide sur plusieurs dizaines de générations. Nos résultats indiquent clairement que les agrégats protéiques sont régis par un mouvement Brownien de diffusion avec un coefficient de diffusion dépendant de la taille de la molécule. L’étude de protéinopathie amyloïde a démontré l’existence de lignages propageant deux types d’agrégats : globulaire ou en forme de "comet-like". Les lignées présentant les agrégats sous forme globulaire indiquent une augmentation de la taille des agrégats jusqu’à inhibition de la division cellulaire tandis que la forme "comet-like" est moins préjudiciable à la croissance. Nous avons également observé à faible fréquence des lignées avec un changement de type d’agrégat. A partir d’un agrégat gobulaire, des agrégats "comet-like" peuvent naître

Dynamique de l'agrégation protéique chez la bactérie Escherichia coli

Protein aggregation plays a key role in cell decline and leads to several human disease linked to ageing like Alzheimer or Parkinson disease and prion disease. In Escherichia coli bacteria, ac- cumulation of damaged proteins and their asymmetric segregation allowed to show ageing signs. This thesis is focused on the in vivo spatial dynamics of protein aggregates in E. coli. Protein aggregates can be classified as inclusion bodies and they are amorphous or amyloid with a high order level due to β sheets. Combining a double theoretical and experimental approach, based on modeling and time-lapse and microfluidic microscopy, we studied the mechanism governing the motion of protein aggregates and the long-term vertical transmission of prionoid aggregates for about 10 generations. Our results show clearly that Brownian diffusion governs the motion of protein aggregates and the diffusion coefficient depends on the molecule size. The amyloid proteinopathy study shows the existence of lineages propagating two kind of aggregates : globular or comet-like. Lineages maintaining globular aggregates present an increase of the aggregate size until inhibition of the growth rate while comet-like aggregates are mildly detrimental to growth. We observed also at low frequency in some lineages the presence of both aggregates and a switch between them. Glo- bular foci give born to comet-like aggregates.L’agrégation protéique joue un rôle clé dans la dégénérescence cellulaire et est notamment reliée à de nombreuses maladies humaines en lien avec le vieillissement telles que les maladies d’Alzheimer et Parkinson ou encore la maladie du prion. Chez la bactérie Escherichia coli, l’accumulation de dommages sous forme d’agrégats protéiques et leur ségrégation asymétrique au pôle ont permis de démontrer des signes de vieillissement chez cette bactérie. Cette thèse s’est concentrée sur l’étude de la dynamique spatiale des agrégats protéiques in vivo chez la bactérie E. coli. Les agrégats protéiques peuvent être classifiés comme corps d’inclusion dont on dit souvent qu’ils sont amorphes ou comme amyloïdes dont le niveau de structuration est très élevée par la présence de nombreux feuillets β. Combinant une double approche théorique et expérimentale, basée sur la modélisation et la microscopie time-lapse et microfluidique, nous avons étudié le mécanisme gouvernant le mouvement des agrégats protéiques et la transmission verticale d’agrégats de type prionoide sur plusieurs dizaines de générations. Nos résultats indiquent clairement que les agrégats protéiques sont régis par un mouvement Brownien de diffusion avec un coefficient de diffusion dépendant de la taille de la molécule. L’étude de protéinopathie amyloïde a démontré l’existence de lignages propageant deux types d’agrégats : globulaire ou en forme de "comet-like". Les lignées présentant les agrégats sous forme globulaire indiquent une augmentation de la taille des agrégats jusqu’à inhibition de la division cellulaire tandis que la forme "comet-like" est moins préjudiciable à la croissance. Nous avons également observé à faible fréquence des lignées avec un changement de type d’agrégat. A partir d’un agrégat gobulaire, des agrégats "comet-like" peuvent naître

Dynamique de l'agrégation protéique chez la bactérie Escherichia coli

Protein aggregation plays a key role in cell decline and leads to several human disease linked to ageing like Alzheimer or Parkinson disease and prion disease. In Escherichia coli bacteria, ac- cumulation of damaged proteins and their asymmetric segregation allowed to show ageing signs. This thesis is focused on the in vivo spatial dynamics of protein aggregates in E. coli. Protein aggregates can be classified as inclusion bodies and they are amorphous or amyloid with a high order level due to β sheets. Combining a double theoretical and experimental approach, based on modeling and time-lapse and microfluidic microscopy, we studied the mechanism governing the motion of protein aggregates and the long-term vertical transmission of prionoid aggregates for about 10 generations. Our results show clearly that Brownian diffusion governs the motion of protein aggregates and the diffusion coefficient depends on the molecule size. The amyloid proteinopathy study shows the existence of lineages propagating two kind of aggregates : globular or comet-like. Lineages maintaining globular aggregates present an increase of the aggregate size until inhibition of the growth rate while comet-like aggregates are mildly detrimental to growth. We observed also at low frequency in some lineages the presence of both aggregates and a switch between them. Glo- bular foci give born to comet-like aggregates.L’agrégation protéique joue un rôle clé dans la dégénérescence cellulaire et est notamment reliée à de nombreuses maladies humaines en lien avec le vieillissement telles que les maladies d’Alzheimer et Parkinson ou encore la maladie du prion. Chez la bactérie Escherichia coli, l’accumulation de dommages sous forme d’agrégats protéiques et leur ségrégation asymétrique au pôle ont permis de démontrer des signes de vieillissement chez cette bactérie. Cette thèse s’est concentrée sur l’étude de la dynamique spatiale des agrégats protéiques in vivo chez la bactérie E. coli. Les agrégats protéiques peuvent être classifiés comme corps d’inclusion dont on dit souvent qu’ils sont amorphes ou comme amyloïdes dont le niveau de structuration est très élevée par la présence de nombreux feuillets β. Combinant une double approche théorique et expérimentale, basée sur la modélisation et la microscopie time-lapse et microfluidique, nous avons étudié le mécanisme gouvernant le mouvement des agrégats protéiques et la transmission verticale d’agrégats de type prionoide sur plusieurs dizaines de générations. Nos résultats indiquent clairement que les agrégats protéiques sont régis par un mouvement Brownien de diffusion avec un coefficient de diffusion dépendant de la taille de la molécule. L’étude de protéinopathie amyloïde a démontré l’existence de lignages propageant deux types d’agrégats : globulaire ou en forme de "comet-like". Les lignées présentant les agrégats sous forme globulaire indiquent une augmentation de la taille des agrégats jusqu’à inhibition de la division cellulaire tandis que la forme "comet-like" est moins préjudiciable à la croissance. Nous avons également observé à faible fréquence des lignées avec un changement de type d’agrégat. A partir d’un agrégat gobulaire, des agrégats "comet-like" peuvent naître

Comparison of color and body condition between early and late breeding King Penguins

Early breeding is associated with greater reproductive success in many species. In king penguins, Aptenodytes patagonicus, laying extends for 6 mo. Early breeders may fledge a single chick at best, but late breeders virtually never fledge a chick. For early and late breeders, we compared colored ornaments known to be important in mate choice: yellow-orange feathers of the breast and auricular areas, and an ultraviolet and yellow-orange beak spot. Our purpose was to discern differences between males and females in this highly sexually monomorphic species, as well as to discern whether colored ornaments are more important for the more successful early breeders (aspects of color were hue, chroma, and brightness). For this, we weighed and measured 130 penguins. Early males had greater reflectance of ultraviolet color from the beak spot than did early females and late breeders of both sexes, and the early males were heavier and in better condition than late breeding males or females. Late breeding females were the yellowest in breast hue, a trait that has been linked to immunocompetence. Within pairs, males and females were significantly correlated in body mass, but only early in the breeding season. We concluded that early in the breeding season when reproductive success was greatest, potential mates were not only more similar in body mass, but also that females may have chosen males that had brighter beak spots and were in better body condition

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

26 p.-9 fig.-11 sup. fig.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. © 2014 John Wiley & Sons Ltd.This work has been supported by grants of the Agence Nationale de la Recherche France,Institut National de la Santé et de la RechercheMédicale–Institut National de Recherche en Informatique et en Automatique projet d’envergure and Axa Foundation Chair on Longevity to A.B.L.; and from Spanish MINECO (BIO2009-06952 and CSD2009-00088) to R.G.Peer reviewe

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

BackgroundRecessive 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

Localization of the detected aggregates in the cells.

<p>(<i>A</i>) In each image on the time-lapse fluorescence movies, the bacterial cells are automatically isolated (each individual cell is given a unique random color). The aggregates appearing during the movie are automatically detected and their trajectory within the cell quantified (internal trajectories). (<i>B</i>) By convention, we referred to the projection of the aggregate location on the long axis of the cell as the <i>x</i>-component and that along the short axis as the <i>y</i>-component. (<i>C</i>) Histogram of the <i>x</i>-component of the initial position of the trajectories (total of 1,644 trajectories). Since the cell length at the start of the trajectory is highly variable, the <i>x</i>-component was rescaled by division by the cell half-length. After this normalization, the cell poles are located at locations −1.0 and 1.0 respectively, for every trajectory. (<i>D</i>) Experimentally measured positions of the aggregates detected in the poles (both poles pooled, <i>n</i> = 9,242 points). The green-dashed curves in (<i>D</i>–<i>F</i>) locate the 2d projection of the 3d semi-ellipsoid that was used to approximate the cell pole. (<i>E</i>) Synthetic data for bulk positions: 10,000 3d positions were drawn uniformly at random in the 3d semi-ellipsoid pole. The figure shows the corresponding 2d projections. (<i>F</i>) Synthetic data of membranary positions: 10,000 3d positions were drawn uniformly at random in the external boundary (membrane) of the 3d semi-ellipsoid pole. The figure shows the corresponding 2d projections. (<i>G</i>) To quantify figures D–F, the correlation function <i>ρ</i>(<i>s</i>) was computed as the density of positions located within crescent <i>D</i>(<i>s</i>) (gray). See text for more detail. (<i>H–I</i>) Local density of aggregate positions <i>ρ</i>(<i>s</i>) in the synthetic (<i>H</i>) and experimental (<i>I</i>) data shown in <i>E</i> (bulk, blue), <i>F</i> (membranary, red) and <i>D</i> (experimental, orange). The dashed black line shows the local density computed for 10,000 synthetic <i>2</i>d positions that were drawn uniformly at random in the 2d semi-ellipse resulting from the 2d projection of the 3d pole ellipsoid (green dashed curve in <i>D–F</i>).</p