Cellular interaction through LewisX cluster: theoretical studies

It is well known that cell surface carbohydrates play a role in cell–cell adhesion and communication. LewisX glycosphingolipids form microdomains on cell surfaces. Homotypic and calcium-mediated LewisX–LewisX (LeX-LeX) interactions were proposed to be responsible for the initial steps of cell adhesion, and to mediate embryogenesis and metastasis. Various techniques have been used to investigate such interactions, but little information is available on the geometry and the mechanism of dimerisation. To better understand these interactions, a new molecular model was developed to simulate homotypic interactions in explicit solvent with and without calcium ions. Accurate analysis of both trajectories yielded valuable information about the energetics of LeX-LeX dimerisation. Detailed interpretation of the hydrogen bond network and the presence of calcium ions along the trajectory provide valuable insights into the role of calcium ions in this carbohydrate–carbohydrate interaction. Figure Calcium population density around the LewisX carbohydrate (after the trajectory has been fitted to the primary unit cell). All central dimer coordinates are fitted along the time axis, whereas calcium ion positions are recorded and represented as points. The clouds of points indicate that the ions are not randomly placed around the dimer but take up preferred positions