MYRISTOYLATION, METHOD TO PREPARE ORIENTED PROTEINS FOR SOLID STATE NMR

University Of Pennsylvania, Philadelphia PA

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Abstract

Our approach to structure determination by solid-state NMR spectroscopy of oriented samples requires that the protein be immobilized in a suitable matrix with uniaxial molecular orientation. The potential to incorporate a membrane anchoring myristoyl group at the amino terminal glycine of any protein is evaluated. The initial results obtained on the immunoglobulin-binding domain of Protein G, a 56-residue protein are promising. The protein was myristoylated in E. coli by coexpression with yeast N-myristoyl transferase and myristic acid. The myristoylated Protein G was then inserted into a membrane bilayer and oriented on glass plates. The two-dimensional PISEMA spectrum which correlates 15N chemical shift and 15N-1H dipolar couplings, indicates that the protein is immobile and oriented along with the bilayer, confirming the original premise that the myristoylation would anchor the protein to the bilayer. The PISEMA spectrum was back- calculated using the coordinates derived from the previously determined solution NMR structure. The orientation of the long axis of the protein parallel to the bilayer normal was revealed based on the best fit to the data.