Detergent Screening for NMR-Based Structural Study of the Integral Membrane Protein, Emopamil Binding Protein (Human Sterol Δ8-Δ7 Isomerase)

Abstract

Human sterol <TEX>${\Delta}8-{\Delta}7$</TEX> isomerase, commonly known as emopamil binding protein (EBP), is an essential protein in the cholesterol-synthetic pathway, and mutations of this protein are critically associated with human diseases such as Conradi-Hunermann-Happle or male EBP disorder with neurological defects syndrome. Due to such a clinical importance, EBP has been intensively investigated and some important features have been reported. EBP is a tetra-spanning membrane protein, of which <TEX>$2^{nd}$</TEX>, <TEX>$3^{rd}$</TEX>, and <TEX>$4^{th}$</TEX> membrane-spanning <TEX>${\alpha}$</TEX> helices play an important role in its enzymatic function. However, detailed structural feature at atomic resolution has not yet been elucidated, due to characteristic difficulties in dealing with membrane protein. Here, we over-expressed EBP using Escherichia coli and performed detergent screening to find suitable membrane mimetics for structural studies of the protein by NMR. As results, DPC and LMPG could be evaluated as the most favorable detergents to acquire promising NMR spectra for structural study of EBP.