The role of membrane-mediated interactions in the assembly and architecture of chemoreceptor lattices

• Published in: PLoS computational biology Vol. 10; no. 12; p. e1003932
• Main Authors: Haselwandter, Christoph A, Wingreen, Ned S
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 01.12.2014; Public Library of Science (PLoS)
• Subjects: Architecture; Bacteria; Biology and Life Sciences; Cell Membrane - chemistry; Cell Membrane - metabolism; Cell Membrane - ultrastructure; Chemoreceptors; Computational Biology; E coli; Escherichia coli; Escherichia coli Proteins - chemistry; Escherichia coli Proteins - metabolism; Experiments; Kinases; Lipid Bilayers - chemistry; Lipid Bilayers - metabolism; Lipids; Microscopy; Models, Biological; Models, Molecular; Physical Sciences; Physiological aspects; Protein research; Protein-protein interactions; Proteins; Receptors, Cell Surface - chemistry; Receptors, Cell Surface - metabolism; Receptors, Cell Surface - ultrastructure; Signal transduction; Tomography
• ISSN: 1553-7358; 1553-734X; 1553-7358
• DOI: 10.1371/journal.pcbi.1003932

In vivo fluorescence microscopy and electron cryo-tomography have revealed that chemoreceptors self-assemble into extended honeycomb lattices of chemoreceptor trimers with a well-defined relative orientation of trimers. The signaling response of the observed chemoreceptor lattices is remarkable for its extreme sensitivity, which relies crucially on cooperative interactions among chemoreceptor trimers. In common with other membrane proteins, chemoreceptor trimers are expected to deform the surrounding lipid bilayer, inducing membrane-mediated anisotropic interactions between neighboring trimers. Here we introduce a biophysical model of bilayer-chemoreceptor interactions, which allows us to quantify the role of membrane-mediated interactions in the assembly and architecture of chemoreceptor lattices. We find that, even in the absence of direct protein-protein interactions, membrane-mediated interactions can yield assembly of chemoreceptor lattices at very dilute trimer concentrations. The model correctly predicts the observed honeycomb architecture of chemoreceptor lattices as well as the observed relative orientation of chemoreceptor trimers, suggests a series of "gateway" states for chemoreceptor lattice assembly, and provides a simple mechanism for the localization of large chemoreceptor lattices to the cell poles. Our model of bilayer-chemoreceptor interactions also helps to explain the observed dependence of chemotactic signaling on lipid bilayer properties. Finally, we consider the possibility that membrane-mediated interactions might contribute to cooperativity among neighboring chemoreceptor trimers.