389113 Morphological Characterization of Detergent-Mediated Photosystem I (PS I)-Proteoliposome Formation

Thursday, November 20, 2014: 10:12 AM
International 5 (Marriott Marquis Atlanta)
Hanieh Niroomand, Chemical and Biomolecular Engineering, Sustainble Energy and Education Research Center (SEERC), The University of Tennessee, Knoxville, TN, Bamin Khomami, Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN and Dibyendu Mukherjee, Mechanical, Aerospace and Biomedical Engineering, Sustainble Energy and Education Research Center (SEERC), The University of Tennessee, Knoxville, TN

In-vitro functional and structural studies of membrane proteins rely on suitable choice of synthetic membrane mimics (e.g., detergents and liposomes) that maintain the protein function1. To this end, we investigate the  interaction of two nonionic detergents n-dodecyl-β-D-maltoside (DDM) and Triton X-100 (TX-100) with two phospholipids, namely  DPhPC (1,2-diphytanoyl-sn-glycero-3-phosphocholine) and DPPG (1,2-dipalmitoyl-sn-glycero-3-phospho-(1'-rac-glycerol)), that commonly constitute the natural thylakoid membrane housing of Photosystem I (PS I), the photosynthetic protein complex. We use optical density and dynamic light scattering (DLS) measurements in conjunction with advanced transmission electron microscopy (TEM) techniques (namely, negative staining and cryo-TEM) to study the detailed mechanistic picture behind processes that drive membrane bilayers to undergo complex structural arrangements during different stages of detergent-mediated solublization.. Specifically, negative staining and cryo-TEM images are used to investigate the solution-phase morphological arrangement of PS I-proteoliposomes. These characterizations provide a fundamental understanding of the role of detergent-mediated protein reconstitution in driving unidirectional arrangements of PS I trimeric complexes within lipid vesicles during PS I-lipid interactions in colloidal solutions. In turn, the aforementioned studies provide valuable insight into mimicking the naturally occurring protein-phospholipid interactions in cell membranes. In future, these bio-mimetic systems shall facilitate easy incorporation of membrane protein-lipid complexes into novel bio-hybrid devices.


  1. Dewald A.H., Hodges J.C., Columbus L. Biophys J. 2011; 100(9): 2131–2140

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