Division of Rheumatology, Inflammation and Immunity Brigham and Women's Hospital, Harvard Medical School, Boston, United States
Hendrik R Sikkema
Department of Biochemistry, University of Groningen Groningen Biomolecular Sciences and Biotechnology Institute, Groningen, Netherlands
Aike Jeucken
Department of Biochemistry, University of Groningen Groningen Biomolecular Sciences and Biotechnology Institute, Groningen, Netherlands
Branch Moody
Division of Rheumatology, Inflammation and Immunity Brigham and Women's Hospital, Harvard Medical School, Boston, United States; Department of Medicine, Harvard Medical School, Boston, United States
Yeast tolerates a low pH and high solvent concentrations. The permeability of the plasma membrane (PM) for small molecules is low and lateral diffusion of proteins is slow. These findings suggest a high degree of lipid order, which raises the question of how membrane proteins function in such an environment. The yeast PM is segregated into the Micro-Compartment-of-Can1 (MCC) and Pma1 (MCP), which have different lipid compositions. We extracted proteins from these microdomains via stoichiometric capture of lipids and proteins in styrene-maleic-acid-lipid-particles (SMALPs). We purified SMALP-lipid-protein complexes by chromatography and quantitatively analyzed periprotein lipids located within the diameter defined by one SMALP. Phospholipid and sterol concentrations are similar for MCC and MCP, but sphingolipids are enriched in MCP. Ergosterol is depleted from this periprotein lipidome, whereas phosphatidylserine is enriched relative to the bulk of the plasma membrane. Direct detection of PM lipids in the 'periprotein space' supports the conclusion that proteins function in the presence of a locally disordered lipid state.
