Uryupina Tatiana A, Bobyleva Liya G, Penkov Nikita V, Timchenko Maria A, Gabdulkhakov Azat G, Glyakina Anna V, Rogachevsky Vadim V, Surin Alexey K, Galzitskaya Oxana V, Vikhlyantsev Ivan M, Bobylev Alexander G
Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, 142290 Pushchino, Russia.
Institute of Cell Biophysics, Federal Research Center Pushchino Scientific Center for Biological Research, Russian Academy of Sciences, 142290 Pushchino, Russia.
Int J Mol Sci. 2025 Jul 18;26(14):6910. doi: 10.3390/ijms26146910.
Protein association and aggregation are fundamental processes that play critical roles in a variety of biological phenomena from cell signaling to the development of incurable diseases, including amyloidoses. Understanding the basic biophysical principles governing protein aggregation processes is of crucial importance for developing treatment strategies for diseases associated with protein aggregation, including sarcopenia, as well as for the treatment of pathological processes associated with the disruption of functional protein complexes. This work, using a set of methods such as atomic force microscopy (AFM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction, as well as bioinformatics analysis, investigated the structures of complexes formed by titin and myosin-binding protein C (MyBP-C). TEM revealed the formation of morphologically ordered aggregates in the form of beads during co-incubation of titin and MyBP-C under close-to-physiological conditions (175 mM KCl, pH 7.0). AFM showed the formation of a relatively homogeneous film with local areas of relief change. Fluorimetry with thioflavin T, as well as FTIR spectroscopy, revealed signs of an amyloid-like structure, including a signal in the cross-β region. X-ray diffraction showed the presence of a cross-β structure characteristic of amyloid aggregates. Such structural features were not observed in the control samples of the investigated proteins separately. In sarcomeres, these proteins are associated with each other, and this interaction plays a partial role in the formation of a strong sarcomeric cytoskeleton. We found that under physiological ionic-strength conditions titin and MyBP-C form complexes in which an amyloid-like structure is present. The possible functional significance of amyloid-like aggregation of these proteins in muscle cells in vivo is discussed.
蛋白质缔合和聚集是基本过程，在从细胞信号传导到包括淀粉样变性在内的不治之症的发展等各种生物现象中发挥着关键作用。了解控制蛋白质聚集过程的基本生物物理原理对于开发与蛋白质聚集相关疾病（包括肌肉减少症）的治疗策略以及治疗与功能性蛋白质复合物破坏相关的病理过程至关重要。这项工作使用了一系列方法，如原子力显微镜（AFM）、透射电子显微镜（TEM）、傅里叶变换红外光谱（FTIR）和X射线衍射，以及生物信息学分析，研究了肌联蛋白和肌球蛋白结合蛋白C（MyBP-C）形成的复合物的结构。TEM显示，在接近生理条件（175 mM KCl，pH 7.0）下，肌联蛋白和MyBP-C共同孵育时，会形成珠状形态有序的聚集体。AFM显示形成了具有局部起伏变化区域的相对均匀的薄膜。用硫黄素T进行的荧光测定以及FTIR光谱显示出淀粉样结构的迹象，包括在交叉β区域的信号。X射线衍射显示存在淀粉样聚集体特有的交叉β结构。在分别研究的蛋白质的对照样品中未观察到此类结构特征。在肌节中，这些蛋白质相互关联，这种相互作用在形成强大的肌节细胞骨架中起部分作用。我们发现，在生理离子强度条件下，肌联蛋白和MyBP-C形成存在淀粉样结构的复合物。讨论了这些蛋白质在体内肌肉细胞中淀粉样聚集的可能功能意义。
