Protein folding on the ribosome studied using NMR spectroscopy

Abstract

Highlights

• •

  Despite size of ribosome, flexible regions can be observed by solution-state NMR.

• •

  Development of NMR methods for the direct observation of co-translational folding.

• •

  We review all NMR studies of ribosome–nascent chain complexes published to date.

• •

  Large, dilute and unstable nature of samples presents a challenging target for NMR.

• •

  In-depth review of strategies to improve experimental sensitivity.

Abstract

NMR spectroscopy is a powerful tool for the investigation of protein folding and misfolding, providing a characterization of molecular structure, dynamics and exchange processes, across a very wide range of timescales and with near atomic resolution. In recent years NMR methods have also been developed to study protein folding as it might occur within the cell, in a de novo manner, by observing the folding of nascent polypeptides in the process of emerging from the ribosome during synthesis. Despite the 2.3 MDa molecular weight of the bacterial 70S ribosome, many nascent polypeptides, and some ribosomal proteins, have sufficient local flexibility that sharp resonances may be observed in solution-state NMR spectra. In providing information on dynamic regions of the structure, NMR spectroscopy is therefore highly complementary to alternative methods such as X-ray crystallography and cryo-electron microscopy, which have successfully characterized the rigid core of the ribosome particle. However, the low working concentrations and limited sample stability associated with ribosome–nascent chain complexes means that such studies still present significant technical challenges to the NMR spectroscopist. This review will discuss the progress that has been made in this area, surveying all NMR studies that have been published to date, and with a particular focus on strategies for improving experimental sensitivity.