Section: New Results

Dynamics of protein aggregation in Escherichia coli

H. Berry, Anne-Sophie Coquel (Beagle) and Ariel Lindner (INSERM U1001, Cochin Medical School, Paris).

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, accumulation of damaged proteins and their asymmetric segregation allowed to show ageing signs. This work [14] 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 $\beta$ 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. Globular foci give born to comet-like aggregates.