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OlyA – A Tool to Study Sphingomyelin‐Cholesterol Interactions in Plasma Membranes
Author(s) -
Endapally Shreya,
Radhakrishnan Arun
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.629.4
Subject(s) - sphingomyelin , membrane , cholesterol , chemistry , biochemistry , microbiology and biotechnology , biophysics , biology
Sphingomyelin (SM) and cholesterol are lipids that are critical for the function of animal cells. Interplay between these two lipids is important for maintaining integrity of the myelin sheath that encases axonal cells and for maintaining functionally distinct pools of cholesterol in the plasma membranes of fibroblast cells. The nature of the interaction between SM and cholesterol has been long debated, with proposals ranging from complexes of the two lipids to no specific interaction between these two lipids. Here, we have developed a tool to examine the interaction between SM and cholesterol in animal cell membranes. Our tool is derived from a fungal toxin, ostreolysin A (OlyA). We find that OlyA binds to membranes of CHO‐K1 hamster cells when they contain both SM and cholesterol, but not when levels of either lipid are diminished by treatment with sphingomyelinase (which degrades SM) or cyclodextrin (which depletes cholesterol). In model membranes, OlyA shows no binding to 1, 2‐dioleoyl‐sn‐glycero‐3‐phosphocholine (DOPC) – cholesterol membranes even when the cholesterol concentration exceeds 50 mole%. Also, OlyA shows no binding to SM‐containing membranes when epicholesterol (a diasteromer of cholesterol) is present at concentration exceeding 50 mole%. These observations combined with direct binding experiments have given us insights into OlyA's dual lipid specificity and into how SM and cholesterol are organized in membranes. Support or Funding Information This work was supported by the Welch Foundation (I‐1793) and the American Heart Association (12SDG12040267).