Articles by Argyris Politis in JoVE
Combining Chemical Cross-linking and Mass Spectrometry of Intact Protein Complexes to Study the Architecture of Multi-subunit Protein Assemblies Caroline Haupt*1, Tommy Hofmann*1, Sabine Wittig*1, Susann Kostmann1, Argyris Politis2, Carla Schmidt1 1Interdisciplinary research center HALOmem, Martin Luther University Halle-Wittenberg, 2Department of Chemistry, Kings College London The architecture of protein complexes is essential for their function. Combining various mass spectrometric techniques proved powerful to study their assembly. We provide protocols for chemical cross-linking and native mass spectrometry and show how these complementary techniques help to elucidate the architecture of multi-subunit protein assemblies.
Other articles by Argyris Politis on PubMed
Uncovering the Early Assembly Mechanism for Amyloidogenic β2-Microglobulin Using Cross-linking and Native Mass Spectrometry The Journal of Biological Chemistry. | Pubmed ID: 26655720 β2-Microglobulin (β2m), a key component of the major histocompatibility class I complex, can aggregate into fibrils with severe clinical consequences. As such, investigating the structural aspects of the formation of oligomeric intermediates of β2m and their subsequent progression toward fibrillar aggregates is of great importance. However, β2m aggregates are challenging targets in structural biology, primarily due to their inherent transient and heterogeneous nature. Here we study the oligomeric distributions and structures of the early intermediates of amyloidogenic β2m and its truncated variant ΔN6-β2m. We established compact oligomers for both variants by integrating advanced mass spectrometric techniques with available electron microscopy maps and atomic level structures from NMR spectroscopy and x-ray crystallography. Our results revealed a stepwise assembly mechanism by monomer addition and domain swapping for the oligomeric species of ΔN6-β2m. The observed structural similarity and common oligomerization pathway between the two variants is likely to enable ΔN6-β2m to cross-seed β2m fibrillation and allow the formation of mixed fibrils. We further determined the key subunit interactions in ΔN6-β2m tetramer, revealing the importance of a domain-swapped hinge region for formation of higher order oligomers. Overall, we deliver new mechanistic insights into β2m aggregation, paving the way for future studies on the mechanisms and cause of amyloid fibrillation.
Hybrid Mass Spectrometry: Towards Characterization of Protein Conformational States Trends in Biochemical Sciences. | Pubmed ID: 27211036 A current challenge in structural biology is to unravel the conformational states of protein complexes. Hybrid mass spectrometry (MS) has emerged as a key tool to study the structural dynamics of large protein complexes unattainable by traditional methods. Here, we discuss recent advances in hybrid MS allowing characterization of challenging biological systems.
Structural Characterisation of Medically Relevant Protein Assemblies by Integrating Mass Spectrometry with Computational Modelling Journal of Proteomics. | Pubmed ID: 28461040 Structural mass spectrometry with its various techniques is a powerful tool for the structural elucidation of medically relevant protein assemblies. It delivers information on the composition, stoichiometries, interactions and topologies of these assemblies. Most importantly it can deal with heterogeneous mixtures and assemblies which makes it universal among the conventional structural techniques. In this review we summarise recent advances and challenges in structural mass spectrometric techniques. We describe how the combination of the different mass spectrometry-based methods with computational strategies enable structural models at molecular levels of resolution. These models hold significant potential for helping us in characterizing the function of protein assemblies related to human health and disease.