Biomolecular Condensates: Structure, Functions, Methods of Research.

The term "biomolecular condensates" is used to describe membraneless compartments in eukaryotic cells, accumulating proteins and nucleic acids. Biomolecular condensates are formed as a result of liquid-liquid phase separation (LLPS). Often, they demonstrate properties of liquid-like droplets or gel-like aggregates; however, some of them may appear to have a more complex structure and high-order organization. Membraneless microcompartments are involved in diverse processes both in cytoplasm and in nucleus, among them ribosome biogenesis, regulation of gene expression, cell signaling, and stress response. Condensates properties and structure could be highly dynamic and are affected by various internal and external factors, e.g., concentration and interactions of components, solution temperature, pH, osmolarity, etc. In this review, we discuss variety of biomolecular condensates and their functions in live cells, describe their structure variants, highlight domain and primary sequence organization of the constituent proteins and nucleic acids. Finally, we describe current advances in methods that characterize structure, properties, morphology, and dynamics of biomolecular condensates in vitro and in vivo.

The Aß42 Peptide and IAPP Physically Interact in a Yeast-Based Assay.

Numerous studies have demonstrated that people with type 2 diabetes mellitus (associated with IAPP peptide aggregation) show an increased incidence of Alzheimer's disease (associated with Aß aggregation), but the mechanism responsible for this correlation is presently unknown. Here, we applied a yeast-based model to study the interactions of IAPP with PrP (associated with TSEs) and with the Aß42 peptide. We demonstrated that fluorescently tagged IAPP forms detergent-resistant aggregates in yeast cells. Using the FRET approach, we showed that IAPP and Aß aggregates co-localize and physically interact in yeast cells. We also showed that this interaction is specific and that there is no interaction between IAPP and PrP in the yeast system. Our data confirmed a direct physical interaction between IAPP and Aß42 aggregates in a living cell. Based on these findings, we hypothesize that this interaction may play a crucial role in seeding Aß42 aggregation in T2DM patients, thereby promoting the development of AD.