Exploring the Aggregation Propensity of PHF6 Peptide Segments of the Tau Protein Using Ion Mobility Mass Spectrometry Techniques

Iuliia Stroganova, Hannah Willenberg, Thaleia Tente, Agathe Depraz Depland, Sjors Bakels, Anouk M. Rijs*

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Peptide and protein aggregation involves the formation of oligomeric species, but the complex interplay between oligomers of different conformations and sizes complicates their structural elucidation. Using ion mobility mass spectrometry (IM-MS), we aim to reveal these early steps of aggregation for the Ac-PHF6-NH2 peptide segment from tau protein, thereby distinguishing between different oligomeric species and gaining an understanding of the aggregation pathway. An important factor that is often neglected, but which can alter the aggregation propensity of peptides, is the terminal capping groups. Here, we demonstrate the use of IM-MS to probe the early stages of aggregate formation of Ac-PHF6-NH2, Ac-PHF6, PHF6-NH2, and uncapped PHF6 peptide segments. The aggregation propensity of the four PHF6 segments is confirmed using thioflavin T fluorescence assays and transmission electron microscopy. A novel approach based on post-IM fragmentation and quadrupole selection on the TIMS-Qq-ToF (trapped ion mobility) spectrometer was developed to enhance oligomer assignment, especially for the higher-order aggregates. This approach pushes the limits of IM identification of isobaric species, whose signatures appear closer to each other with increasing oligomer size, and provides new insights into the interpretation of IM-MS data. In addition, TIMS collision cross section values are compared with traveling wave ion mobility (TWIMS) data to evaluate potential instrumental bias in the trapped ion mobility results. The two IM-MS instrumental platforms are based on different ion mobility principles and have different configurations, thereby providing us with valuable insight into the preservation of weakly bound biomolecular complexes such as peptide aggregates.

Original languageEnglish
Pages (from-to)5115-5124
Number of pages10
JournalAnalytical chemistry
Volume96
Issue number13
Early online date22 Mar 2024
DOIs
Publication statusPublished - 2 Apr 2024

Bibliographical note

Publisher Copyright:
© 2024 The Authors. Published by American Chemical Society.

Funding

The authors gratefully acknowledge funding from the research program VICI with project number VI.C.192.024 and Aspasia (015.015.009) from the Dutch Research Council (NWO) awarded to A.M.R. We would like to thank Jan R.T. van Weering for the help with TEM experiments, Christopher A. Wootton from Bruker, Jan Commandeur, Steven Daly, and Jerre van der Horst from MS Vision for helpful discussions.

FundersFunder number
Nederlandse Organisatie voor Wetenschappelijk Onderzoek

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