Myosin Binding Protein-C Forms Amyloid-Like Aggregates In Vitro

• Main Authors: Liya G. Bobyleva, Sergey A. Shumeyko, Elmira I. Yakupova, Alexey K. Surin, Oxana V. Galzitskaya, Hiroshi Kihara, Alexander A. Timchenko, Maria A. Timchenko, Nikita V. Penkov, Alexey D. Nikulin, Mariya Yu. Suvorina, Nikolay V. Molochkov, Mikhail Yu. Lobanov, Roman S. Fadeev, Ivan M. Vikhlyantsev, Alexander G. Bobylev
• Format: Article
• Language: English
• Published: MDPI AG 2021-01-01
• Series: International Journal of Molecular Sciences
• Subjects: muscle proteins; MyBP-C; amyloid; amyloid-like aggregation; protein aggregation; structural analysis
• Online Access: https://www.mdpi.com/1422-0067/22/2/731
• ISSN: 1661-6596; 1422-0067

This work investigated in vitro aggregation and amyloid properties of skeletal myosin binding protein-C (sMyBP-C) interacting in vivo with proteins of thick and thin filaments in the sarcomeric A-disc. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) found a rapid (5–10 min) formation of large (>2 μm) aggregates. sMyBP-C oligomers formed both at the initial 5–10 min and after 16 h of aggregation. Small angle X-ray scattering (SAXS) and DLS revealed sMyBP-C oligomers to consist of 7–10 monomers. TEM and atomic force microscopy (AFM) showed sMyBP-C to form amorphous aggregates (and, to a lesser degree, fibrillar structures) exhibiting no toxicity on cell culture. X-ray diffraction of sMyBP-C aggregates registered reflections attributed to a cross-β quaternary structure. Circular dichroism (CD) showed the formation of the amyloid-like structure to occur without changes in the sMyBP-C secondary structure. The obtained results indicating a high in vitro aggregability of sMyBP-C are, apparently, a consequence of structural features of the domain organization of proteins of this family. Formation of pathological amyloid or amyloid-like sMyBP-C aggregates in vivo is little probable due to amino-acid sequence low identity (<26%), alternating ordered/disordered regions in the protein molecule, and S–S bonds providing for general stability.