Similar to the macroscopic machines that perform important functions in daily life, microscopic molecular machines play a crucial role in cellular activities. These are often regulated by communication between different regions of the molecule. Several examples are presented here that focus on solution NMR spectroscopic investigations from machines that are important for protein quality control in the cell. In particular, it highlights the unique role of NMR in such studies, highlighting that applications to systems with aggregate molecular weights of several hundred kilodaltons are now possible and that the findings from NMR studies are highly complementary to those obtained via X-rays – and electron cryomicroscopy approaches.
Developments in solution NMR spectroscopy have significantly influenced the biological issues that can now be addressed with this methodology. By way of illustration, we present here a perspective that focuses on studying a number of molecular machines that are critical to cellular homeostasis. The role of NMR in elucidating the structural dynamics of these important molecules is emphasized, with an emphasis on allosteric communication between subunits in homo-oligomers. Many biophysical studies of oligomers suggest allostery by showing that models that specifically involve communication between subunits best fit the data of interest. Ideally, however, experimental studies focusing on one subunit of a multi-subunit system would be conducted as an important addition to the more traditional mass measurements in which signals from all components are measured simultaneously. Using an approach that uses asymmetric molecules in conjunction with NMR experiments that focus on the structural dynamics of individual protomers, we present examples of how allostery between subunits in high molecular weight protein systems can be directly observed. These examples highlight some of the unique roles of solution NMR spectroscopy in studying complex biomolecules and highlight the important synergy between NMR and other biophysical methods with atomic resolution.
- Accepted October 27, 2021.
This post is part of the special series of Inaugural Articles by the 2020 National Academy of Sciences elected members.
Author contributions: YT and LEK wrote the paper.
The authors do not declare any competing interests.
This article is a PNAS direct submission.