title: Lipid-Mediated Regulation of Embedded Receptor Kinases via Parallel Allosteric Relays.
abstract: Membrane-anchored receptors are essential cellular signaling elements for stimulus sensing, propagation, and transmission inside cells. However, the contributions of lipid interactions to the function and dynamics of embedded receptor kinases have not been described in detail. In this study, we used amide hydrogen/deuterium exchange mass spectrometry, a sensitive biophysical approach, to probe the dynamics of a membrane-embedded receptor kinase, EnvZ, together with functional assays to describe the role of lipids in receptor kinase function. Our results reveal that lipids play an important role in regulating receptor function through interactions with transmembrane segments, as well as through peripheral interactions with nonembedded domains. Specifically, the lipid membrane allosterically modulates the activity of the embedded kinase by altering the dynamics of a glycine-rich motif that is critical for phosphotransfer from ATP. This allostery in EnvZ is independent of membrane composition and involves direct interactions with transmembrane and periplasmic segments, as well as peripheral interactions with nonembedded domains of the protein. In the absence of the membrane-spanning regions, lipid allostery is propagated entirely through peripheral interactions. Whereas lipid allostery impacts the phosphotransferase function of the kinase, extracellular stimulus recognition is mediated via a four-helix bundle subdomain located in the cytoplasm, which functions as the osmosensing core through osmolality-dependent helical stabilization. Our findings emphasize the functional modularity in a membrane-embedded kinase, separated into membrane association, phosphotransferase function, and stimulus recognition. These components are integrated through long-range communication relays, with lipids playing an essential role in regulation.
authors.affiliation: Department of Biological Sciences, National University of Singapore, Singapore.
authors.forename: Madhubrata
authors.initials: M
authors.lastname: Ghosh
authors.affiliation: School of Biological Sciences, Nanyang Technological University, Singapore.
authors.forename: Loo Chien
authors.initials: LC
authors.lastname: Wang
authors.affiliation: Department of Biological Sciences, National University of Singapore, Singapore.
authors.forename: Ranita
authors.initials: R
authors.lastname: Ramesh
authors.affiliation: Jesse Brown Veteran Affairs Medical Center, Chicago, Illinois; Department of Microbiology and Immunology, University of Illinois at Chicago, Chicago, Illinois.
authors.forename: Leslie K
authors.initials: LK
authors.lastname: Morgan
authors.affiliation: Department of Biological Sciences, National University of Singapore, Singapore; Jesse Brown Veteran Affairs Medical Center, Chicago, Illinois; Department of Microbiology and Immunology, University of Illinois at Chicago, Chicago, Illinois; Mechanobiology Institute, National University of Singapore, Singapore. Electronic address: kenneyl@uic.edu.
authors.forename: Linda J
authors.initials: LJ
authors.lastname: Kenney
authors.affiliation: Department of Biological Sciences, National University of Singapore, Singapore. Electronic address: dbsgsa@nus.edu.sg.
authors.forename: Ganesh S
authors.initials: GS
authors.lastname: Anand
mesh_terms: D000494:Allosteric Regulation; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism*; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism; D056004:Molecular Dynamics Simulation; D009097:Multienzyme Complexes / Q000737:chemistry / Q000378:metabolism*; D009994:Osmolar Concentration; D010743:Phospholipids / Q000378:metabolism*; D010766:Phosphorylation; D011487:Protein Conformation; D017433:Protein Structure, Secondary
chemical_list: D001425:Bacterial Outer Membrane Proteins; D029968:Escherichia coli Proteins; D008051:Lipid Bilayers; D009097:Multienzyme Complexes; D010743:Phospholipids; C057843:envZ protein, E coli