title: Structural diversity of a collagen-binding matrix protein from the byssus of blue mussels upon refolding.
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 preCols 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.
authors.affiliation: Lehrstuhl Biomaterialien, Fakultät für Ingenieurwissenschaften, Universität Bayreuth, Universitätsstraße 30, 95440 Bayreuth, Germany.
authors.forename: Michael H
authors.initials: MH
authors.lastname: Suhre
authors.affiliation: Lehrstuhl Biomaterialien, Fakultät für Ingenieurwissenschaften, Universität Bayreuth, Universitätsstraße 30, 95440 Bayreuth, Germany; Bayreuther Zentrum für Kolloide und Grenzflächen (BZKG), Universität Bayreuth, Universitätsstraße 30, 95440 Bayreuth, Germany; Institut für Bio-Makromoleküle (bio-mac), Universität Bayreuth, Universitätsstraße 30, 95440 Bayreuth, Germany; Bayreuther Zentrum für Molekulare Biowissenschaften (BZMB), Universität Bayreuth, Universitätsstraße 30, 95440 Bayreuth, Germany; Bayreuther Materialzentrum (BayMAT), Universität Bayreuth, Universitätsstraße 30, 95440 Bayreuth, Germany. Electronic address: thomas.scheibel@bm.uni-bayreuth.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Scheibel
mesh_terms: D000818:Animals; D016326:Extracellular Matrix Proteins / Q000737:chemistry*; D008958:Models, Molecular; D049880:Mytilus edulis; D054730:Protein Interaction Domains and Motifs; D058849:Protein Refolding; D055550:Protein Stability; D017433:Protein Structure, Secondary; D013816:Thermodynamics
chemical_list: D016326:Extracellular Matrix Proteins
keywords: Disulfide isomers; Proximal Thread Matrix Protein 1 (PTMP1); Refolding; Structural stability; VWA domains