Protein structural studies by paramagnetic solid-state NMR spectroscopy aided by a compact cyclen-type Cu(II) binding tag.
Protein structural studies by paramagnetic solid-state NMR spectroscopy aided by a compact cyclen-type Cu(II) binding tag.
J Biomol NMR. 2014 Nov 29;
Authors: Sengupta I, Gao M, Arachchige RJ, Nadaud PS, Cunningham TF, Saxena S, Schwieters CD, Jaroniec CP
Abstract
Paramagnetic relaxation enhancements (PREs) are a rich source of structural information in protein solid-state NMR spectroscopy. Here we demonstrate that PRE measurements in natively diamagnetic proteins are facilitated by a thiol-reactive compact, cyclen-based, high-affinity Cu(2+) binding tag, 1-[2-(pyridin-2-yldisulfanyl)ethyl]-1,4,7,10-tetraazacyclododecane (TETAC), that overcomes the key shortcomings associated with the use of larger, more flexible metal-binding tags. Using the TETAC-Cu(2+) K28C mutant of B1 immunoglobulin-binding domain of protein G as a model, we find that amino acid residues located within ~10*? of the Cu(2+) center experience considerable transverse PREs leading to severely attenuated resonances in 2D (15)N-(13)C correlation spectra. For more distant residues, electron-nucleus distances are accessible via quantitative measurements of longitudinal PREs, and we demonstrate such measurements for (15)N-Cu(2+) distances up to ~20*?.
PMID: 25432438 [PubMed - as supplied by publisher]
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