Decoding the Structural Behaviors of Membrane Protein-Detergent Complex Using Scanning HPLC/SAXS/UV-vis System
Yi-Qi Yeh1*, Kuei-Fen Liao1, Orion Shih1, Wei-Ru Wu1, Chun-Jen Su1, Po-Chang Lin1, Kun-Mou Li2, Jia-Yin Tsai2, Yuh-Ju Sun2, U-Ser Jeng1,3
1Experimental Facility Division, National Synchrotron Radiation Research Center, Hsin-Chu, Taiwan
2Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsin-Chu, Taiwan
3Department of Chemical Engineering, National Tsing Hua University, Hsin-Chu, Taiwan
* presenting author:Yi-Qi Yeh, email:yeh.yq@nsrrc.org.tw
The SAXS structural investigation of the transmembrane protein have been retarded by two obstacles: (1) The inevitable coexistence of the protein-detergent complex and the free micelles. (2) The detergent corona completely reshapes the scattering curve of the protein.
We have developed an on-line high-performanc liquid chrotomography (HPLC) system at 23A small- and wide-angle X-ray scattering (SAXS/WAXS) endstation of the National Synchrotron Radiation Research Center (NSRRC), Taiwan [1]. Further incorporated with an UV-Vis absorption spectrometer at the sample area, the HPLC/SAXS/UV-vis system allows separating the coexisting protein-detergent complex and the free detergent micelles. The only one obstacle to overcome is to model the detergent corona of the protein-detergent complex. Recently, Javier et. al reported a methodology to solve the corona modelling. The Memprot program [2] is to model the detergent corona around the membrane protein of known structure.
In this work, the n-decyl-β-D-maltopyranoside (DM) detergent corona around the Vigna radiata H+-translocating Pyrophosphatase (VrH+-PPase), a transmembrane protein of known structure (pdb: 4A01) [3].
The Memprot modelling result revealed that the thickness of DM corona, shaped as elliptical torus, agrees with the thickness of the transmembrane region of VrH+-PPase deduced from the crystal structure. The in-plane orientation of DM elliptical corona showed parallel to the z axis of the isotropic VrH+-PPase structure. The HPLC/SAXS/UV-vis system and detergent corona modelling methodology can provide membrane protein/detergent (or lipid) a potential approach to understand the structural behaviors of membrane protein in solution.

References
[1] Jeng, U-S., Su, C. H., Su, C. J., Liao, K. F., et al. J. (2010) Appl. Cryst. 43, 110–121.
[2] Pe´reza, J, Koutsioubasb, A. Acta Cryst. (2015). D71, 86–93
[3] Lin, S. M., Tsai, J. Y., Hsiao, C. D., Huang, Y. T., et al. (2012) Nature 484, 399-403.


Keywords: HPLC/SAXS, membrane protein