Language
English
Publication Date
3-26-2024
Journal
Proceedings of the National Academy of Sciences of the United States of America
DOI
10.1073/pnas.2321606121
PMID
38513106
PMCID
PMC10990091
PubMedCentral® Posted Date
3-21-2024
Abstract
Eukaryotic cells form condensates to sense and adapt to their environment [S. F. Banani, H. O. Lee, A. A. Hyman, M. K. Rosen, Nat. Rev. Mol. Cell Biol. 18, 285–298 (2017), H. Yoo, C. Triandafillou, D. A. Drummond, J. Biol. Chem. 294, 7151–7159 (2019)]. Poly(A)-binding protein (Pab1), a canonical stress granule marker, condenses upon heat shock or starvation, promoting adaptation [J. A. Riback et al., Cell 168, 1028–1040.e19 (2017)]. The molecular basis of condensation has remained elusive due to a dearth of techniques to probe structure directly in condensates. We apply hydrogen–deuterium exchange/mass spectrometry to investigate the mechanism of Pab1’s condensation. Pab1’s four RNA recognition motifs (RRMs) undergo different levels of partial unfolding upon condensation, and the changes are similar for thermal and pH stresses. Although structural heterogeneity is observed, the ability of MS to describe populations allows us to identify which regions contribute to the condensate’s interaction network. Our data yield a picture of Pab1’s stress-triggered condensation, which we term sequential activation (Fig. 1A), wherein each RRM becomes activated at a temperature where it partially unfolds and associates with other likewise activated RRMs to form the condensate. Subsequent association is dictated more by the underlying free energy surface than specific interactions, an effect we refer to as thermodynamic specificity. Our study represents an advance for elucidating the interactions that drive condensation. Furthermore, our findings demonstrate how condensation can use thermodynamic specificity to perform an acute response to multiple stresses, a potentially general mechanism for stress-responsive proteins.
Keywords
Poly(A)-Binding Proteins, Temperature, Heat-Shock Proteins, Thermodynamics, Heat-Shock Response, Deuterium Exchange Measurement
Published Open-Access
yes
Recommended Citation
Chen, Ruofan; Glauninger, Hendrik; Kahan, Darren N; et al., "HDX-MS Finds That Partial Unfolding With Sequential Domain Activation Controls Condensation of a Cellular Stress Marker" (2024). Faculty, Staff and Students Publications. 8243.
https://digitalcommons.library.tmc.edu/baylor_docs/8243