Analysis of the solution conformations of T4 lysozyme by paramagnetic NMR spectroscopy.
Related Articles Analysis of the solution conformations of T4 lysozyme by paramagnetic NMR spectroscopy.
Phys Chem Chem Phys. 2016 Feb 17;18(8):5850-9
Authors: Chen JL, Yang Y, Zhang LL, Liang H, Huber T, Su XC, Otting G
Abstract
A large number of crystal structures of bacteriophage T4 lysozyme (T4-L) have shown that it contains two subdomains, which can arrange in a compact conformation (closed state) or, in mutants of T4-L, more extended structures (open state). In solution, wild-type T4-L displays only a single set of nuclear magnetic resonance (NMR) signals, masking any conformational heterogeneity. To probe the conformational space of T4-L, we generated a site-specific lanthanide binding site by attaching 4-mercaptomethyl dipicolinic acid via a disulfide bond to Cys44 in the triple-mutant C54T/C97A/S44C of T4-L and measured pseudocontact shifts (PCS) and magnetically induced residual dipolar couplings (RDC). The data indicate that, in solution and in the absence of substrate, the structure of T4-L is on average more open than suggested by the closed conformation of the crystal structure of wild-type T4-L. A slightly improved fit was obtained by assuming a population-weighted two-state model involving an even more open conformation and the closed state, but paramagnetic relaxation enhancements measured with Gd(3+) argue against such a conformational equilibrium. The fit could not be improved by including a third conformation picked from the hundreds of crystal structures available for T4-L mutants.
PMID: 26680012 [PubMed - indexed for MEDLINE]
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