Native Mass Spectrometry and Complementary Techniques to Characterize Biological Macromolecular Assemblies

Download or read book Native Mass Spectrometry and Complementary Techniques to Characterize Biological Macromolecular Assemblies written by Andrew S. Norris and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The structures adopted by biological macromolecules and macromolecular complexes are directly tied to their function. By better understanding the relationship between structure and function of biomolecules, lifesaving and life-changing interventions can be designed such as small molecule inhibitors of viral enzymes. Characterization of macromolecules with high-resolution structural techniques has greatly improved our fundamental understanding of how structures dictate function. High-resolution structural techniques including x-ray crystallography, cryo-electron microscopy, and nuclear magnetic resonance spectroscopy, however, have many challenges and so they require complementary techniques. Native mass spectrometry is one such technique that can be used to interrogate macromolecular assemblies and accurately determine molecular weight(s), oligomeric state(s), ligand-binding, and topology of the assembly. Native mass spectrometry has the advantage of not being limited by some of the common issues encountered by high-resolution techniques like molecular flexibility and sample heterogeneity that can limit resolution attainable or prevent structure determination altogether. This attribute is particularly valuable for the characterization of protein-nucleic acid complexes that have proven to be some of the more challenging complexes for high-resolution techniques. Throughout this work, native mass spectrometry is emphasized as a clear approach for examining differences in macromolecular assemblies that highlight the structural diversity of macromolecular systems which would otherwise not be evident. Chapter 3 describes identification of the physiological protein interface of a plant protein, BX1.This approach demonstrates the use of native mass spectrometry and covalent cross-linking mass spectrometry to solve a common issue with X-ray crystallography, namely artificial protein contacts formed during the crystallization process. Chapter 4 describes the investigation of the assembly pathway for RNase P, a multi-subunit archaeal ribonucleoprotein. Additionally, native mass spectrometry addresses the absence of a protein subunit in the cryo-EM structure of the same RNase P. Chapter 5 describes the investigation of the different assembly states of DNA annealing proteins. A cryo-EM reconstruction of a section of one of the protein-DNA complexes was determined. For this protein, native mass spectrometry complemented the cryo-EM study by determining the composition of the entire complex. With the native mass spectrometry assembly data for DNA annealing proteins and the cryo-EM for one of these proteins, proposed revisions to the current model of single-strand annealing are presented. Finally, in Chapter 6, cooperative ligand binding of three cyclic homo-oligomers is reported and a cooperative binding model, the nearest-neighbor model, was used to fit the data to quantitively determine thermodynamic parameters. RNA binding was also tested, but work is still ongoing. Overall, the work presented herein demonstrates the use of native mass spectrometry to study the assembly states of macromolecular complexes and hereby gain insights not easily accessible by other structural techniques.