Biology subjects

Jawed, J. J.

Publications and source records attributed to Jawed, J. J..

3 recordsLinked to original sources

bioRxiv2024

Mechanism of host cell invasion by Leishmania through KMP-11 mediated cholesterol-transport and membrane phase transition

The first step of successful infection by any intracellular pathogen relies on its ability to invade its host cell membrane. However, the detailed structural and molecular understanding underlying lipid membrane modification during pathogenic invasion remains unclear. In this study, we show that a specific Leishmania donovani (LD) protein, KMP-11, forms oligomers that bridge LD and host macrophage (M{Phi}) membranes. This KMP-11 induced interaction between LD and M{Phi} depends on the variations in cholesterol (CHOL) and ergosterol (ERG) contents in their respective membranes. These variations are crucial for the subsequent steps of invasion, including (a) the initial attachment, (b) CHOL transport from M{Phi} to LD, and (c) detachment of LD from the initial point of contact through a liquid ordered (Lo) to liquid disordered (Ld) membrane-phase transition. To validate the importance of KMP-11, we generated KMP-11 depleted LD, which failed to attach and invade host M{Phi}. Through tryptophan-scanning mutagenesis and synthesized peptides, we developed a generalized mathematical model, which demonstrates that the hydrophobic moment and the symmetry sequence code at the membrane interacting protein domain are key factors in facilitating the membrane phase transition and, consequently, the host cell infection process by Leishmania parasites.

biophysics↗

bioRxiv2020

Protein induced membrane phase transition facilitates leishmania infection

Although host membrane is known to play critical roles in the internalization of leishmania parasites inside macrophages (M{phi}), any detailed mechanistic understanding is missing. We show here that KMP-11, a small immunogenic protein of Leishmania Donovani (LD) facilitates the infection process by binding to M{phi} membrane through its N-terminal domain (1-19AA). This binding results in a membrane phase transition that occurs at a threshold protein/lipid ratio, which is linked to the change in membrane tension. KMP-11 induced phase transition is also associated with lipid raft disruption and T-cell deactivation. Finally, using a combination of tryptophan-scanning mutagenesis and synthesized peptides, we develop a mathematical exposition, which demonstrates that hydrophobic moment (H) and the number of residues involved in a mirror sequence (N) at the interacting N-terminal are governing factors for the membrane phase transition, which facilitates infection process.

biophysics↗

bioRxiv2018

Vitexin alters Staphylococcus aureus surface hydrophobicity to interfere with biofilm formation.

Bacterial surface hydrophobicity is one of the determinant biophysical parameters of bacterial aggregation for being networked to form biofilm. Phytoconstituents like vitexin have long been in use for their antibacterial effect. The present work is aimed to characterise the effect of vitexin on S. aureus surface hydrophobicity and corresponding aggregation to form biofilm. We have found that vitexin shows minimum inhibitory concentration at 252 g/ml against S. aureus. Vitexin reduces cell surface hydrophobicity and membrane permeability at sub-MIC dose of 126 g/ml. The in silico binding analysis showed higher binding affinity of vitexin with surface proteins of S. aureus. Down regulation of dltA, icaAB and reduction in membrane potential under sub-MIC dose of vitexin, explains reduced S. aureus surface hydrophobicity. Vitexin has substantially reduced the intracellular adhesion of planktonic cells to form biofilm through interference of EPS formation, motility and subsequent execution of virulence. This was supported by the observation that vitexin down regulates the expression of icaAB and agrAC genes of S. aureus. In addition, vitexin also found to potentiate antibiofilm activity of sub-MIC dose of gentamicin and azithromycin. Furthermore, CFU count, histological examination of mouse tissue and immunomodulatory study justifies the in vivo protective effect of vitexin from S. aureus biofilm associated infection. Finally it can be inferred that, vitexin has the ability to modulate S. aureus cell surface hydrophobicity which can further interfere biofilm formation of the bacteria.\n\nImportanceThere has been substantial information known about role of bacterial surface hydrophobicity during attachment of single planktonic bacterial cells to any surface and the subsequent development of mature biofilm. This study presents the effect of flavone phytoconstituent vitexin on modulation of cell surface hydrophobicity in reducing formation of biofilm. Our findings also highlight the ability of vitexin in reducing in vivo S. aureus biofilm which will eventually outcompete the corresponding in vitro antibiofilm effect. Synergistic effect of vitexin on azithromycin and gentamicin point to a regime where development of drug tolerance may be addressed. Our findings explore one probable way of overcoming drug tolerance through application of vitexin in addressing the issue of S. aureus biofilm through modulation of cell surface hydrophobicity.

microbiology↗