ISM 2022 (Microscopy)


Nimrod Golan Amit Parizat Meytal Landau
Biology, Technion - Israel Institute of Technology, Haifa, Israel

Amyloid study has advanced significantly over the past few decades, especially in eukaryotes where amyloids are thought to contribute to neurodegenerative and other systemic diseases; yet, amyloids are also found in many other organisms and can carry out various physiological processes. They are especially prevalent in microbes and were identified as key virulence factors, thus microbial amyloids represent attractive candidates for structural characterization aimed at discovering novel antimicrobial therapeutics. However, amyloids are challenging systems for biochemical and structural studies due to their polymeric arrangement and aggregative, polymorphic, and partially disordered nature. We have devoted much of our recent study efforts on three well-known families of amyloid proteins: Enterobacteria Curli, Pseudomonas Fap, and Candida Als. Our recent studies have resolved the structures, as well as evaluated the functional significance of amyloidogenic peptide segments within the adhesion protein Als5 of Candida albicans. Additionally, we investigated the interaction between FapB and FapC, two predominating amyloid proteins of Pseudomonas aeruginosa. We illustrated how they are affected by different growth conditions, like pH and temperature, and how their interactions tend to produce fibrils that are much more resistant to harsh environmental conditions. These results might suggest a different "distribution of labor" between the proteins than previously suggested. A detailed description of the structure and activity of microbial amyloid proteins will allow us to better deal with infections caused by these pathogens, and even repurpose their role to utilize to our benefit the potential inherent in them.

FapB&C interaction and chemical dissolution effects.(A) Fluorescence microscopy images of FapB&C labeled with Cyanine3 (Cy3) and Cyanine5 (Cy5) fluorophores, respectively. (B) The quantified amount of monomer received in SDS-PAGE after incubation with formic acid of FapB&C fibrils. The graph represents the relative change in the number of monomers. Error bars indicate the standard errors from the mean of three experimental repeats. (C) TEM images of negatively stained FapC and FapC + FapB fibrils after incubation with formic acid.  Scale bars represent 0.4μm for all TEM images.