Biology subjects

Ganar, K. A.

Publications and source records attributed to Ganar, K. A..

3 recordsLinked to original sources

bioRxiv2025

pH-Responsive Phase Separation Dynamics of Intrinsically Disordered Peptides

Liquid-liquid phase separation of biomolecules is crucial for maintaining the functional organization in biological systems. Intrinsically disordered proteins are particularly prone to form phase-separated condensates in response to various physicochemical triggers. While the effect of ionic strength and temperature on phase separation dynamics have been studied extensively, the influence of pH is less explored. Here, we study a model glycine-rich protein present in the tick bioadhesive, given its capability to undergo phase separation. After confirming its disordered nature through spectroscopy, we investigated its pH dependence and underlying molecular mechanisms. Our findings reveal that pH significantly influences the protein hydrophobicity via ionic residues, driving notable variations in the coacervation behavior (propensity, progression) and in shaping the material properties (viscosity, interfacial activity) of the formed condensates. Given the ubiquitous presence of disordered proteins in biology, this study provides valuable insights about the broad implications of the pH-dependent behavior of intrinsically disordered proteins.

biochemistry↗

bioRxiv2024

Regulating biocondensates within synthetic cells via segregative phase separation

Living cells orchestrate a myriad of biological reactions within a highly complex and crowded environment. A major factor responsible for such seamless assembly are the preferential interactions between the constituent macromolecules, either associative or segregative, that can drive de-mixing to produce co-existing phases, and thus provide a dynamic intracellular compartmentalization. But how these two types of interactions, occurring simultaneously within the cytoplasmic space, influence each other is still largely unknown. This makes understanding and applying the molecular interactions that interfere with each other in such crowded environments crucial when engineering increasingly complex synthetic cells. Here, we show that the interplay between segregative and associative phase separation within cell-mimicking vesicles can lead to rich dynamics between them. Using on-chip microfluidic systems, we encapsulate the associative and segregative components in cell-sized containers and trigger their phase separations to create hierarchical structures that act as molecular recruiters, membrane targeting agents, and initiators of condensation. The obtained multiphase architecture provides an isolated microenvironment for condensates, restricting their molecular communication as well as diffusive motion, and leading to budding-like behaviour at the lipid membrane. In conclusion, we propose segregative phase separation as a universal condensate regulation strategy in managing molecular distribution, condensate location, as well as membrane interaction. We believe our approach will facilitate controlling the behaviour of membraneless organelles within synthetic cells.

synthetic biology↗

bioRxiv2023

Phase Separation and Ageing of Glycine-Rich Protein from Tick Adhesive

Hard ticks feed on their host for multiple days. To ensure firm attachment, they secrete a protein-rich saliva that eventually forms a solid cement cone. The underlying mechanism of this liquid-to-solid transition is not yet understood. This study focuses on the phase transitions of a disordered glycine-rich protein (GRP) that is prominent in tick saliva. We show that GRP undergoes liquid-liquid phase separation via simple coacervation to form biomolecular condensates in salty environments. Cation-pi and pi-pi interactions near the C-terminus promote coacervation while a negatively charged N-terminus prolongs its onset through electrostatic repulsion. Interestingly, GRP condensates exhibit ageing and undergo liquid-to-gel transition to form viscoelastic networks as well as solid-like condensates. Lastly, we provide evidence for protein-rich condensates in natural tick saliva. Our findings provide a starting point to gain insights into the bioadhesion of ticks, develop novel tick control strategies, and towards biomedical applications such as tissue sealants.

biochemistry↗