Neurofilament Light Protein Rod Domain Exhibits Structural Heterogeneity

• Published in: Biomolecules (Basel, Switzerland) Vol. 14; no. 1; p. 85
• Main Authors: Nefedova, Victoria V, Kleymenov, Sergey Y, Safenkova, Irina V, Levitsky, Dmitrii I, Matyushenko, Alexander M
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 01-01-2024
• Subjects: AF4 platform; Amino acids; Analysis; Calorimetry; Calorimetry, Differential Scanning; Circular dichroism; coiled-coil structure; Cytoplasmic filaments; Differential scanning calorimetry; Identification and classification; Inclusion; Intermediate Filaments; Methods; Mutation; neurofilament light chain; Neurofilaments; Neurons; Polymerization; Properties; Protein Domains; protein stability; Proteins; Self-association; Spectroscopy; Spectrum analysis; Thermal denaturation; Thermal stability; Tumor Necrosis Factor Ligand Superfamily Member 14; United Kingdom; coiled-coil structure; neurofilament light chain; circular dichroism; protein stability; differential scanning calorimetry; AF4 platform
• ISSN: 2218-273X; 2218-273X
• DOI: 10.3390/biom14010085

Neurofilaments are neuron-specific proteins that belong to the intermediate filament (IFs) protein family, with the neurofilament light chain protein (NFL) being the most abundant. The IFs structure typically includes a central coiled-coil rod domain comprised of coils 1A, 1B, and 2, separated by linker regions. The thermal stability of the IF molecule plays a crucial role in its ability for self-association. In the current study, we investigated the thermal stability of NFL coiled-coil domains by analyzing a set of recombinant domains and their fusions (NFL
, NFL
, NFL
, NFL
, and NFL
) via circular dichroism spectroscopy and differential scanning calorimetry. The thermal stability of coiled-coil domains is evident in a wide range of temperatures, and thermal transition values (T
) correspond well between isolated coiled-coil domains and full-length NFL. NFL
has a T
of 39.4 °C, and its' fusions, NFL
and NFL
, have a T
of 41.9 °C and 41.5 °C, respectively. However, in the case of NFL
, thermal denaturation includes at least two thermal transitions at 37.2 °C and 62.7 °C. These data indicate that the continuous α-helical structure of the coil 2 domain has parts with varied thermal stability. Among all the NFL fragments, only NFL
underwent irreversible heat-induced denaturation. Together, these results unveil the origin of full-length NFL's thermal transitions, and reveal its domains structure and properties.