@article {47098, title = {Role of cholesterol in transmembrane dimerization of the ErbB2 growth factor receptor}, journal = {Journal of Membrane Biology}, year = {2021}, month = {JAN}, type = {Article; Early Access 2021}, abstract = {

The association of ErbB2 growth factor receptors is critical for cell growth and potentiates tumor proliferation in several cancer types. An important aspect in ErbB2 association is the role of lipids such as cholesterol, especially since their metabolism is often reprogrammed in cancer cells. Here, we have coupled metadynamics with coarse-grain simulations to identify cholesterol effects in the transmembrane dimerization of ErbB2 receptors. Overall, cholesterol interactions are observed with the receptor that directly tunes the association energetics. Several dimer conformations are identified both in the presence and absence of cholesterol, although the dimer regime appears to be more favorable in the presence of cholesterol. We observe an overall modulation of the underlying energy profile and the symmetric active and inactive conformational states are not distinguished in the presence of cholesterol. We show that cholesterol binds to the receptor transmembrane domain at a site (CRAC motif) that overlaps with the dimer interface (SmXXXSm motif). The competition between the transmembrane interactions and cholesterol interactions decides the final conformational landscape. Our work is an important step toward characterizing cholesterol effects in ErbB2 membrane receptor function. [GRAPHICS] .

}, keywords = {Cholesterol, ErbB2 growth factor receptor, Her2 dimer, Juxtamembrane dimer, Martini coarse-grain simulations, Metadynamics}, issn = {0022-2631}, doi = {10.1007/s00232-021-00168-z, Early Access Date = JAN 2021}, author = {Pawar, Aiswarya B. and Sengupta, Durba} } @article {48347, title = {Synergistic and competitive lipid interactions in the serotonin1A receptor microenvironment}, journal = {ACS Chemical Neuroscience}, volume = {13}, year = {2022}, month = {DEC }, pages = {3403-3415}, type = {Article}, abstract = {

The interaction of lipids with G-protein-coupled receptors (GPCRs) has been shown to modulate and dictate several aspects of GPCR organization and function. Diverse lipid interaction sites have been identified from structural biology, bioinformatics, and molecular dynamics studies. For example, multiple cholesterol interaction sites have been identified in the serotonin1A receptor, along with distinct and overlapping sphingolipid interaction sites. How these lipids interact with each other and what is the resultant effect on the receptor is still not clear. In this work, we have analyzed lipid-lipid crosstalk at the receptor of the serotonin1A receptor embedded in a membrane bilayer that mimics the neuronal membrane composition by long coarse-grain simulations. Using a set of similarity coefficients, we classified lipids that bind at the receptor together as synergistic cobinding, and those that bind individually as competitive. Our results show that certain lipids interact with the serotonin1A receptor in synergy with each other. Not surprisingly, the ganglioside GM1 and cholesterol show a synergistic cobinding, along with the relatively uncommon GM1-phosphatidylethanolamine (PE) and cholesterol-PE synergy. In contrast, certain lipid pairs such as cholesterol and sphingomyelin appear to be in competition at several sites, despite their coexistence in lipid nanodomains. In addition, we observed intralipid competition between two lipid tails, with the receptor exhibiting increased interactions with the unsaturated lipid tails. We believe our work represents an important step in understanding the diversity of GPCR-lipid interactions and exploring synergistic cobinding and competition in natural membranes.

}, keywords = {GPCR, lipid crosstalk, Martini coarse-grain simulations, Membrane cholesterol, neuronal membranes}, issn = {1948-7193}, doi = {10.1021/acschemneuro.2c00422}, author = {Mohole, Madhura and Sengupta, Durba and Chattopadhyay, Amitabha} } @article {48442, title = {Cofilin-membrane interactions: electrostatic effects in phosphoinositide lipid binding}, journal = {ChemPhysChem}, volume = {24}, year = {2023}, month = {FEB }, type = {Article}, abstract = {

The actin cytoskeleton interacts with the cell membrane primarily through the indirect interactions of actin-binding proteins such as cofilin-1. The molecular mechanisms underlying the specific interactions of cofilin-1 with membrane lipids are still unclear. Here, we performed coarse-grain molecular dynamics simulations of cofilin-1 with complex lipid bilayers to analyze the specificity of protein-lipid interactions. We observed the maximal interactions with phosphoinositide (PIP) lipids, especially PIP2 and PIP3 lipids. A good match was observed between the residues predicted to interact and previous experimental studies. The clustering of PIP lipids around the membrane bound protein leads to an overall lipid demixing and gives rise to persistent membrane curvature. Further, through a series of control simulations, we observe that both electrostatics and geometry are critical for specificity of lipid binding. Our current study is a step towards understanding the physico-chemical basis of cofilin-PIP lipid interactions.

}, keywords = {complex membrane, lipid clustering, Martini coarse-grain simulations, Molecular dynamics simulations, Protein-lipid interactions}, issn = {1439-4235}, doi = {10.1002/cphc.202200509}, author = {Prakash, Shikha and Krishna, Anjali and Sengupta, Durba} }