Change in local dynamics of bacteriorhodopsin with retinal isomerization under pressure as studied by fast magic angle spinning NMR

Abstract

Bacteriorhodopsin (bR) has a retinal with all-trans and 13-cis, 15-syn configurations whose isomeric ratio is close to 1 in the dark-adapted bR, and the population of the 13-cis, 15-syn configuration can be increased under pressure. In our previous study, we applied pressure to bR using centrifugal force introduced by sample spinning and demonstrated that the 15 N nuclear magnetic resonance (NMR) signal intensity of the Schiff base in 13-cis, 15-syn retinal increased. In this study, we demonstrate a pressure-induced change in the local dynamics of the protein side in the vicinity of retinal. In the 13 C dipolar decoupling and magic angle-spinning NMR spectra of [3-13 C]Ala-labeled bR under fast spinning at 10 and 12 kHz, corresponding to 44 and 63 bar, respectively, the 13 C NMR signal at 16.6 p.p.m. appeared prominently as a sharp peak. This peak is assigned to Ala81 and Ala84 residues located in the vicinity of the retinal. It was observed that the change in the local dynamics in the vicinity of the retinal was caused by the applied pressure. These experiments demonstrate that fast magic angle spinning in NMR provides a pressure source for investigating the structure and change in the dynamics of biomacromolecules.

NMR of sedimented, fibrillized, silica-entrapped and microcrystalline (metallo)proteins

“…In this frame, carbonic anhydrase and the catalytic domain of the MMPs have fairly low melting temperatures [84,85], suggesting a comparably low stability toward slightly harder experimental conditions (i.e. : toward the higher pressure that is possibly encountered during MAS-induced sedimentation [86]). …”

On-Pathway Oligomer of Human Islet Amyloid Polypeptide Induced and Stabilized by Mechanical Rotation during Magic Angle Spinning Nuclear Magnetic Resonance

“…The significant mechanical forces, such as centrifugal pressure, involved in MAS additionally offer a novel modulator of the amyloid formation pathway. Previous work has demonstrated the ability of small molecules, peptides, lipid membranes, metals, synthetic polymers, pH, and electric fields to alter amyloid aggregation pathways and in some cases to stabilize oligomeric intermediates for further structural studies. − Pressure as a result of centrifugal forces during MAS has been found to affect the structure and dynamics of bacteriorhodopsins and apoferritin, but its effect on the species formed during amyloid aggregation has not been fully characterized. − Here, we provide the first report, to the best of our knowledge, of the ability of the mechanical forces associated with MAS to stabilize intermediate, on-pathway aggregates of human islet amyloid polypeptide (hIAPP) in an aqueous environment.…”

Recent Solid-State NMR Studies of Membrane-Bound Peptides and Proteins

“…This peak was assigned to Ala81 and Ala84 which are located in the vicinity of retinal. It was observed that changes in local dynamics in the vicinity of retinal were caused by the application of pressure [168].…”