Analysis of the solution structure of Thermosynechococcus elongatus photosystem I in n-dodecyl-β-d-maltoside using small-angle neutron scattering and molecular dynamics simulation

Journal Article · Thu May 01 00:00:00 EDT 2014 · Archives of Biochemistry and Biophysics

DOI:https://doi.org/10.1016/j.abb.2014.04.005· OSTI ID:1136117

Le, Rosemary K. ^[1]; Harris, Bradley J. ^[1]; Iwuchukwu, Ifeyinwa J. ^[1]; Bruce, Barry D. ^[1]; Cheng, Xiaolin ^[2]; Qian, Shuo  ^[2]; Heller, William T. ^[2]; O’Neill, Hugh ^[2]; Frymier, Paul D. ^[1]

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1. Univ. of Tennessee, Knoxville, TN (United States)
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Small-angle neutron scattering (SANS) and molecular dynamics (MD) simulation were used to investigate the structure of trimeric photosystem I (PSI) from Thermosynechococcus elongatus (T. elongatus) stabilized in n-dodecyl-β-d-maltoside (DDM) detergent solution. Scattering curves of detergent and protein–detergent complexes were measured at 18% D2O, the contrast match point for the detergent, and 100% D2O, allowing observation of the structures of protein/detergent complexes. It was determined that the maximum dimension of the PSI–DDM complex was consistent with the presence of a monolayer belt of detergent around the periphery of PSI. A dummy-atom reconstruction of the shape of the complex from the SANS data indicates that the detergent envelope has an irregular shape around the hydrophobic periphery of the PSI trimer rather than a uniform, toroidal belt around the complex. A 50 ns MD simulation model (a DDM ring surrounding the PSI complex with extra interstitial DDM) of the PSI–DDM complex was developed for comparison with the SANS data. The results suggest that DDM undergoes additional structuring around the membrane-spanning surface of the complex instead of a simple, relatively uniform belt, as is generally assumed for studies that use detergents to solubilize membrane proteins.

• Research Organization: Blankenship/Washington Univ., St. Louis, MO (United States); Energy Frontier Research Centers (EFRC) (United States). Photosynthetic Antenna Research Center (PARC)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• DOE Contract Number: SC0001035
• OSTI ID: 1136117
• Report Number(s): DOE/SC0001035-114
• Journal Information: Archives of Biochemistry and Biophysics, Vol. 550-551, Issue C; ISSN 0003-9861
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

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