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Satheesh, T.

Publications and source records attributed to Satheesh, T..

2 recordsLinked to original sources

Crosstalk between plasma membrane and Staphylococcus α-hemolysin during oligomerization

The infectious microbe Staphylococcus aureus releases an array of cytotoxic pore-forming toxins (PFTs) that severely damage the cell membrane during bacterial infection. However, the interaction interfaces between the host cell and toxin were merely explored. Herein, we monitored the active oligomeric states facilitated membrane disruption processes such as lysis, and protrusion in the plasma membrane and lipid membrane. Furthermore, necrosis was triggered in the neutrophil-like cells upon synergistic binding and oligomerization of the monomeric -HL. Additionally, we solved RBC membrane stabilized structure of different conformational states of this {beta}-PFT using a single-particle cryo-EM. We further confirmed that internal membrane fluidity was the deterministic factor associated with the formation of intermediate pre-pores, heptameric pore-like, and complete pore species. Together, this is the first study to unveil the structure-function analysis of pre-pore to pore transition of any small {beta}-PFT during its crosstalk with the cell. HighlightsO_LI-HL promotes necrosis in HL60 cells and lysis of shorter lipid bilayer region. C_LIO_LICryo-EM of small PFT in the cellular environment. C_LIO_LIStructural characterization of heptameric pore, pore-like, and pre-pore complex in the presence of RBCs. C_LIO_LIBilayer phase behavior (Ld/Lo) governs different conformational and geometrical variants of -HL. C_LI

biophysics↗

Cryo-EM reveals the mechanism of DNA compaction by Mycobacterium smegmatis Dps2

DNA-binding protein under starvation (Dps), is a miniature ferritin complex which plays a vital role in protecting bacterial DNA during starvation for maintaining the integrity of bacteria from hostile conditions. Mycobacterium smegmatis is one such bacteria that express MsDps2, which binds DNA to protect it under oxidative and nutritional stress conditions. Several approaches, including cryo-electron tomography (Cryo-ET), were implemented to identify the structure of the Dps protein that is bound to DNA. However, none of the structures of the Dps-DNA complex was resolved to high resolution to be able to identify the DNA binding residues. In this study, we implemented various biochemical and biophysical studies to characterize the DNA protein interactions of Dps protein. We employed single-particle cryo-EM-based structural analysis of MsDps2-DNA and identify that the region close to N-terminal confers the DNA binding property. Based on cryo-EM data, we performed mutations of several arginine residues proximal to DNA binding region, which dramatically reduced the MsDps2-DNA interaction. In addition, we demonstrated the proposed model for DNA compaction during lattice formation. We also pinpointed arginine residues, which are responsible for DNA binding in lattice arrangement of MsDps2. We performed single-molecule imaging experiments of MsDps2-DNA interactions that corroborate well with our structural studies.

biophysics↗