Title
The Ca2+ response of a smart forisome protein is dependent on polymerization
Author
Judith Rose, Izabella Brand, Merle Bilstein-Schloemer, Barbara Jachimska, Richard M. Twyman, Dirk Prüfer, Gundula A. Noll
Year
2021
Journal
PROTEIN SCIENCE
Abstract
Forisomes are giant self-assembling mechanoproteins that undergo reversible structural changes in response to Ca2+ and various other stimuli. Artificial forisomes assembled from the monomer MtSEO-F1 can be used as smart biomaterials, but the molecular basis of their functionality is not understood. To determine the role of protein polymerization in forisome activity, we tested the Ca2+ association of MtSEO-F1 dimers (the basic polymerization unit) by circular dichroism spectroscopy and microscale thermophoresis. We found that soluble MtSEO-F1 dimers neither associate with Ca2+ nor undergo structural changes. However, polarization modulation infrared reflection absorption spectroscopy revealed that aggregated MtSEO-F1 dimers and fully-assembled forisomes associate with Ca2+, allowing the hydration of poorly-hydrated protein areas. A change in the signal profile of complete forisomes indicated that Ca2+ interacts with negatively-charged regions in the protein complexes that only become available during aggregation. We conclude that aggregation is required to establish the Ca2+ response of forisome polymers.
Full Article
Instrument
J-1500
Keywords
mechanoproteins, structure, biomaterials, MtSEO-F1,