Site-Resolved Backbone and Side-Chain Intermediate Dynamics in a Carbohydrate-Binding Module Protein Studied by Magic-Angle Spinning NMR Spectroscopy.
Site-Resolved Backbone and Side-Chain Intermediate Dynamics in a Carbohydrate-Binding Module Protein Studied by Magic-Angle Spinning NMR Spectroscopy.
Chemistry. 2015 Jun 12;
Authors: Ivanir-Dabora H, Nimerovsky E, Madhu PK, Goldbourt A
Abstract
Magic-angle spinning solid-state NMR spectroscopy has been applied to study the dynamics of CBM3b-Cbh9A from Clostridium thermocellum (ctCBM3b), a cellulose binding module protein. This 146-residue protein has a nine-stranded ?-sandwich fold, in which 35 % of the residues are in the ?-sheet and the remainder are composed of loops and turns. Dynamically averaged (1) H-(13) C dipolar coupling order parameters were extracted in a site-specific manner by using a pseudo-three-dimensional constant-time recoupled separated-local-field experiment (dipolar-chemical shift correlation experiment; DIPSHIFT). The backbone-C? and C? order parameters indicate that the majority of the protein, including turns, is rigid despite having a high content of loops; this suggests that restricted motions of the turns stabilize the loops and create a rigid structure. Water molecules, located in the crystalline interface between protein units, induce an increased dynamics of the interface residues thereby lubricating crystal water-mediated contacts, whereas other crystal contacts remain rigid.
PMID: 26073185 [PubMed - as supplied by publisher]
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