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.
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.
Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996, United States.
Rosemary K
RK
Le
Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996, United States.
Bradley J
BJ
Harris
Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996, United States.
Ifeyinwa J
IJ
Iwuchukwu
Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, United States; Sustainable Energy Education and Research Center, University of Tennessee, Knoxville, TN 37996, United States.
Barry D
BD
Bruce
Center for Molecular Biophysics, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States; Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, United States.
Xiaolin
X
Cheng
Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States.
Shuo
S
Qian
Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States.
William T
WT
Heller
Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States.
Hugh
H
O'Neill
Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996, United States; Sustainable Energy Education and Research Center, University of Tennessee, Knoxville, TN 37996, United States. Electronic address: pdf@utk.edu.
Paul D
PD
Frymier
D001426:Bacterial Proteins / Q000737:chemistry* / Q000302:isolation & purification; D000458:Cyanobacteria / Q000737:chemistry* / Q000201:enzymology; D003902:Detergents / Q000737:chemistry*; D003903:Deuterium / Q000737:chemistry; D005960:Glucosides / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D008823:Micelles; D008968:Molecular Conformation; D056004:Molecular Dynamics Simulation; D033363:Neutron Diffraction; D045331:Photosystem I Protein Complex / Q000737:chemistry* / Q000302:isolation & purification; D055503:Protein Multimerization; D053838:Scattering, Small Angle; D012996:Solutions
D001426:Bacterial Proteins; D003902:Detergents; D005960:Glucosides; D008823:Micelles; D045331:Photosystem I Protein Complex; D012996:Solutions; C040358:dodecyl maltoside; D003903:Deuterium
Detergent monolayer; Dummy-atom reconstruction; Membrane protein; Small-angle neutron scattering