Dynamics of crowding-induced mixing in phase separated lipid bilayers

Journal Article · Mon Oct 10 00:00:00 EDT 2016 · Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical Chemistry

DOI:https://doi.org/10.1021/acs.jpcb.6b07119· OSTI ID:1335132

Zeno, Wade F. ^[1]; Johnson, Kaitlin E. ^[1]; Sasaki, Darryl Y. ^[2]; Risbud, Subhash H. ^[1]; Longo, Marjorie L. ^[1]

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1. Univ. of California, Davis, CA (United States)
2. Sandia National Lab. (SNL-CA), Livermore, CA (United States)

We use fluorescence microscopy to examine the dynamics of the crowding-induced mixing transition of liquid ordered (L_o)–liquid disordered (L_d) phase separated lipid bilayers when the following particles of increasing size bind to either the L_o or L_d phase: Ubiquitin, green fluorescent protein (GFP), and nanolipoprotein particles (NLPs) of two diameters. These proteinaceous particles contained histidine-tags, which were phase targeted by binding to iminodiacetic acid (IDA) head groups, via a Cu²⁺ chelating mechanism, of lipids that specifically partition into either the Lo phase or Ld phase. The degree of steric pressure was controlled by varying the size of the bound particle (10–240 kDa) and the amount of binding sites present (i.e., DPIDA concentrations of 9 and 12 mol%) in the supported lipid multibilayer platform used here. We develop a mass transfer-based diffusional model to analyze the observed L_o phase domain dissolution that, along with visual observations and activation energy calculations, provides insight into the sequence of events in crowding-induced mixing. Furthermore, our results suggest that the degree of steric pressure and target phase influence not only the efficacy of steric-pressure induced mixing, but the rate and controlling mechanism for which it occurs.

• Research Organization: Sandia National Laboratories (SNL-CA), Livermore, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
• Grant/Contract Number: AC04-94AL85000
• OSTI ID: 1335132
• Report Number(s): SAND--2016-7155J; 646062
• Journal Information: Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical Chemistry, Journal Name: Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical Chemistry Journal Issue: 43 Vol. 120; ISSN 1520-6106
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English

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