10 research outputs found
New insights into lipid-Nucleoside Diphosphate Kinase-D interaction mechanism: Protein structural changes and membrane reorganisation
AbstractNucleoside Diphosphate Kinases (NDPKs) have long been considered merely as housekeeping enzymes. The discovery of the NME1 gene, an anti-metastatic gene coding for NDPK-A, led the scientific community to re-evaluate their role in the cell. It is now well established that the NDPK family is more complex than what was first thought, and despite the increasing amount of evidence suggesting the multifunctional role of nm23/NDPKs, the specific functions of each family member are still elusive. Among these isoforms, NDPK-D is the only one to present a mitochondria-targeting sequence. It has recently been shown that this protein is able to bind and cross-link with mitochondrial membranes, suggesting that NDPK-D can mediate contact sites and contributes to the mitochondrial intermembrane space structuring. To better understand the influence of NDPK-D on mitochondrial lipid organisation, we analysed its behaviour in different lipid environments. We found that NDPK-D not only interacts with CL or anionic lipids, but is also able to bind in a non negligible manner to zwitterionic PC. NDPK-D alters membrane organisation in terms of fluidity, hydration and lipid clustering, effects which depend on lipid structure. Changes in the protein structure after lipid binding were evidenced, both by fluorescence and infrared spectroscopy, regardless of membrane composition. Taking into account all these elements, a putative mechanism of interaction between NDPK-D and zwitterionic or anionic lipids was proposed
Two-Step Membrane Binding of NDPK‑B Induces Membrane Fluidity Decrease and Changes in Lipid Lateral Organization and Protein Cluster Formation
Nucleoside
diphosphate kinases (NDPKs) are crucial elements in
a wide array of cellular physiological or pathophysiological processes
such as apoptosis, proliferation, or metastasis formation. Among the
NDPK isoenzymes, NDPK-B, a cytoplasmic protein, was reported to be
associated with several biological membranes such as plasma or endoplasmic
reticulum membranes. Using several membrane models (liposomes, lipid
monolayers, and supported lipid bilayers) associated with biophysical
approaches, we show that lipid membrane binding occurs in a two-step
process: first, initiation by a strong electrostatic adsorption process
and followed by shallow penetration of the protein within the membrane.
The NDPK-B binding leads to a decrease in membrane fluidity and formation
of protein patches. The ability of NDPK-B to form microdomains at
the membrane level may be related to protein–protein interactions
triggered by its association with anionic phospholipids. Such accumulation
of NDPK-B would amplify its effects in functional platform formation
and protein recruitment at the membrane
PLoS Pathog
Mycolactone is a lipid-like endotoxin synthesized by an environmental human pathogen, Mycobacterium ulcerans, the causal agent of Buruli ulcer disease. Mycolactone has pleiotropic effects on fundamental cellular processes (cell adhesion, cell death and inflammation). Various cellular targets of mycolactone have been identified and a literature survey revealed that most of these targets are membrane receptors residing in ordered plasma membrane nanodomains, within which their functionalities can be modulated. We investigated the capacity of mycolactone to interact with membranes, to evaluate its effects on membrane lipid organization following its diffusion across the cell membrane. We used Langmuir monolayers as a cell membrane model. Experiments were carried out with a lipid composition chosen to be as similar as possible to that of the plasma membrane. Mycolactone, which has surfactant properties, with an apparent saturation concentration of 1 mu M, interacted with the membrane at very low concentrations (60 nM). The interaction of mycolactone with the membrane was mediated by the presence of cholesterol and, like detergents, mycolactone reshaped the membrane. In its monomeric form, this toxin modifies lipid segregation in the monolayer, strongly affecting the formation of ordered microdomains. These findings suggest that mycolactone disturbs lipid organization in the biological membranes it crosses, with potential effects on cell functions and signaling pathways. Microdomain remodeling may therefore underlie molecular events, accounting for the ability of mycolactone to attack multiple targets and providing new insight into a single unifying mechanism underlying the pleiotropic effects of this molecule. This membrane remodeling may act in synergy with the other known effects of mycolactone on its intracellular targets, potentiating these effects