Solution NMR of signal peptidase, a membrane protein.

摘要: Useful solution nuclear magnetic resonance (NMR) data can be obtained from full-length, enzymatically active type I signal peptidase (SPase I), an integral membrane protein, in detergent micelles. Signal has two transmembrane segments, a short cytoplasmic loop, and 27-kD C-terminal catalytic domain. It is critical component of protein transport systems, recognizing cleaving amino-terminal peptides preproteins during the final stage their export. Its structure interactions with substrate are considerable interest, but no three-dimensional whole been reported. The structural analysis intact proteins challenging only recently significant progress achieved using NMR to determine structure. Here we employ spectroscopy study full-length SPase dodecylphosphocholine HSQC-TROSY spectra showed resonances corresponding approximately 3/4 324 residues protein. Some sequential assignments were 3D HNCACB, HNCA, HN(CO) TROSY uniformly 2H, 13C, 15N-labeled I. assigned suggest that observed spectrum dominated by arising extramembraneous portions domain largely absent spectra. Our work elucidates some challenges large micelles as well future promise these kinds studies.