Interplay between Nanoparticle Wrapping and Clustering of Inner Anchored Membrane Proteins

The receptor-mediated endocytosis of nanoparticles (NPs) is known to be size and shape dependent but regulated by membrane properties, like tension, rigidity, and especially membrane proteins. Compared with transmembrane receptors, which directly bind ligands coated on NPs to provide the driving force for passive endocytosis, the hidden role of inner anchored membrane proteins (IAMPs), however, has been grossly neglected. Here, by applying the N-varied dissipative particle dynamics (DPD) techniques, we present the first simulation study on the interplay between wrapping of NPs and clustering of IAMPs. Our results suggest that the wrapping dynamics of NPs can be regulated by clustering of IAMPs, but in a competitive way. In the early stage, the dispersed IAMPs rigidify the membrane and thus restrain NP wrapping by increasing the membrane bending energy. However, once the clustering completes, the rigidifying effect is reduced. Interestingly, the clustering of longer IAMPs can sense NP wrapping. They are found to locate preferentially at the boundary region of NP wrapping. More importantly, the adjacent IAMP clustering produces a late membrane monolayer protrusion, which finally wraps the NP from the top side. Our findings regarding the competitive effects of IAMP clustering on NP wrapping facilitate the molecular understanding of endocytosis and establish fundamental principles for design of NPs for widespread biomedical applications.