Structural diversity of a collagen-binding matrix protein from the byssus of blue mussels upon refolding

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Suhre, Michael H. ; Scheibel, Thomas:
Structural diversity of a collagen-binding matrix protein from the byssus of blue mussels upon refolding.
In: Journal of Structural Biology. Bd. 186 (2014) Heft 1 . - S. 75-85.
ISSN 1047-8477
DOI: https://doi.org/10.1016/j.jsb.2014.02.013

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Abstract

Blue mussels firmly adhere to a variety of different substrates by the byssus, an extracorporal structure
consisting of several protein threads. These threads are mainly composed of fibrillar collagens called pre-
Cols which are embedded in a proteinaceous matrix. One of the two so far identified matrix proteins is
the Proximal Thread Matrix Protein 1 (PTMP1). PTMP1 comprises two von Willebrand factor type A-like
domains (A1 and A2) in a special arrangement. Here, we describe the refolding of recombinant PTMP1
from inclusion bodies. PTMP1 refolded into two distinct monomeric isoforms. Both isomers exhibited
alternative intramolecular disulfide bonds. One of these isomers is thermodynamically favored and presumably
represents the native form of PTMP1, while the other isoform is kinetically favored but is likely
non-native. Oligomerization during refolding was influenced by, but not strictly dependent on disulfide
formation. The conformational stability of PTMP1 indicates an influence of intramolecular disulfides on
the native state, but not on unfolding intermediates. Monomeric PTMP1 exhibited a high thermal stability,
dependent on the pH of the surrounding environment. Especially under acidic conditions the disulfide
bonds were critically involved in thermal stability.