Achinta Sannigrahi

Cellular membranes are dynamic molecular landscapes in which lipid composition, transbilayer asymmetry, membrane curvature, thickness and mechanics collectively shape protein organization and function, while proteins can in turn remodel lipid organization and membrane architecture. Yet lipid-protein interactions are often treated as discrete binding events, obscuring the extent to which the physical organization of the membrane itself constitutes an active determinant of protein conformational states and cellular activity. Here, we investigate lipid-protein reciprocal coupling by integrating quantitative analyses of curvature-dependent protein-membrane association and hydrophobic-run organization with established structural, lipidomic and biochemical evidence. Our analysis reveals substantial variation in protein association with curved versus flat membrane environments and highlights how membrane curvature, together with lipid composition, cholesterol and asymmetry, can regulate protein structure and function, including in disease-associated systems. We further examine emerging lipid sensors, spatial proteomics and advanced biomimetic membrane platforms that are beginning to bridge molecular mechanisms with protein-lipid organization in cells. In particular, suspended membranes, pore-spanning systems and nanopillar architectures offer opportunities to independently control lipid composition, leaflet asymmetry, curvature and mechanics while directly interrogating protein behaviour. Together, these findings support a model in which membrane architecture encodes physical information that is read by proteins and reciprocally reshaped by protein activity to regulate cellular function.

Dengue virus, and other viral pathogens such as SARS-CoV-2 and Zika, utilize specialized glycoproteins to facilitate the fusion of its lipid membrane with that of the host cell, a critical step for viral entry and infection. This membrane fusion process is significantly influenced by factors such as host cell membrane lipid composition, membrane architecture, and cell surface receptors. However, the specific mechanisms by which dengue virus membrane fusion is modulated by the cell membrane lipids are not fully elucidated. We investigate the role of oxidised cholesterol metabolite, 25-hydroxycholesterol (25-HC) in inhibiting dengue virus infection using virus fusion and viral infection assays. We demonstrate that 25-HC significantly impedes the membrane fusion capability of the dengue virus, thereby inhibiting viral entry and infection in cell cultures. Apart from inhibiting membrane fusion, pre-exposure to 25-HC upregulates CH25H which inhibits virus growth. Indeed, CH25H gene is upregulated along with other ISGs in various cell types as a defence response to dengue virus infection. These insights into the modulation of dengue virus membrane fusion by lipid cofactors in the host cell membrane present a promising avenue for the development of strategies aimed at inhibiting viral membrane fusion, thereby potentially curtailing the spread of the infection. For example, we show that other inhibitors that target mechanisms distinct from 25-HC action on membrane fusion display strong positive synergy in virus inhibition with 25-HC.

While peptide‐based drug development is extensively explored, this strategy has limitations due to rapid excretion from the body (or shorter half‐life in the body) and vulnerability to protease‐mediated degradation. To overcome these limitations, a novel strategy for the development of a peptide‐based anticancer agent is introduced, utilizing the conformation switch property of a chameleon sequence stretch (PEP1) derived from a mycobacterium secretory protein, MPT63. The selected peptide is then loaded into a new porous organic polymer (PG‐DFC‐POP) synthesized using phloroglucinol and a cresol derivative via a condensation reaction to deliver the peptide selectively to cancer cells. Utilizing ensemble and single‐molecule approaches, this peptide undergoes a transition from a disordered to an alpha‐helical conformation, triggered by the acidic environment within cancer cells that is demonstrated. This adopted alpha‐helical conformation resulted in the formation of proteolysis‐resistant oligomers, which showed efficient membrane pore‐forming activity selectively for negatively charged phospholipids accumulated in cancer cell membranes. The experimental results demonstrated that the peptide‐loaded PG‐DFC‐POP‐PEP1 exhibited significant cytotoxicity in cancer cells, leading to cell death through the Pyroptosis pathway, which is established by monitoring numerous associated events starting from lysosome membrane damage to GSDMD‐induced cell membrane demolition. This novel conformational switch‐based drug design strategy is believed to have great potential in endogenous environment‐responsive cancer therapy and the development of future drug candidates to mitigate cancers.