Multifunctional Amyloids in the Biology of Gram-Positive Bacteria.

Since they were discovered, amyloids have proven to be versatile proteins able to participate in a variety of cellular functions across all kingdoms of life. This multitask trait seems to reside in their ability to coexist as monomers, aggregates or fibrillar entities, with morphological and biochemical peculiarities. It is precisely this common molecular behaviour that allows amyloids to cross react with one another, triggering heterologous aggregation.

Biofilm formation displays intrinsic offensive and defensive features of .

Biofilm formation is a strategy of many bacterial species to adapt to a variety of stresses and has become a part of infections, contaminations, or beneficial interactions. In this study, we demonstrate that profound physiological changes permit to switch from a floating to a sessile lifestyle, to undergo further maturation of the biofilm and to differentiate into the offensive or defensive features. We report that floating and biofilm cells are populations that differentiate metabolically, with members of each subpopulation developing different branches of certain metabolic pathways.

Two genomic regions encoding exopolysaccharide production systems have complementary functions in B. cereus multicellularity and host interaction.

Bacterial physiology and adaptation are influenced by the exopolysaccharides (EPS) they produce. These polymers are indispensable for the assembly of the biofilm extracellular matrix in multiple bacterial species. In a previous study, we described the profound gene expression changes leading to biofilm assembly in B.

Molecular architecture of bacterial amyloids in biofilms.

The formation of biofilms provides structural and adaptive bacterial response to the environment. In species, the biofilm extracellular matrix is composed of exopolysaccharides, hydrophobins, and several functional amyloid proteins. We report, using multiscale approaches such as solid-state NMR (SSNMR), electron microscopy, X-ray diffraction, dynamic light scattering, attenuated total reflection Fourier transform infrared (FTIR), and immune-gold labeling, the molecular architecture of and pathogenic functional amyloids.