Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390.
Institute for Quantum Life Science, National Institutes for Quantum and Radiological Science and Technology, 263-8555 Chiba, Japan.
Proc Natl Acad Sci U S A. 2021 Feb 23;118(8). doi: 10.1073/pnas.2022121118.
Low complexity (LC) head domains 92 and 108 residues in length are, respectively, required for assembly of neurofilament light (NFL) and desmin intermediate filaments (IFs). As studied in isolation, these IF head domains interconvert between states of conformational disorder and labile, β-strand-enriched polymers. Solid-state NMR (ss-NMR) spectroscopic studies of NFL and desmin head domain polymers reveal spectral patterns consistent with structural order. A combination of intein chemistry and segmental isotope labeling allowed preparation of fully assembled NFL and desmin IFs that could also be studied by ss-NMR. Assembled IFs revealed spectra overlapping with those observed for β-strand-enriched polymers formed from the isolated NFL and desmin head domains. Phosphorylation and disease-causing mutations reciprocally alter NFL and desmin head domain self-association yet commonly impede IF assembly. These observations show how facultative structural assembly of LC domains via labile, β-strand-enriched self-interactions may broadly influence cell morphology.
长度分别为 92 和 108 个残基的低复杂度(LC)头部结构域是神经丝轻链(NFL)和结蛋白中间丝(IF)组装所必需的。在单独研究中,这些 IF 头部结构域在构象无序和不稳定、富含β-折叠的聚合物状态之间相互转换。固态 NMR(ss-NMR)光谱研究表明,NFL 和结蛋白头部结构域聚合物具有结构有序的光谱模式。通过内含肽化学和分段同位素标记的组合,制备了可通过 ss-NMR 研究的完全组装的 NFL 和结蛋白 IF。组装的 IF 显示的光谱与从分离的 NFL 和结蛋白头部结构域形成的富含β-折叠的聚合物形成的光谱重叠。磷酸化和致病突变相互改变 NFL 和结蛋白头部结构域的自我缔合,但通常会阻碍 IF 的组装。这些观察结果表明,通过不稳定的富含β-折叠的自我相互作用进行 LC 结构域的选择性结构组装如何广泛影响细胞形态。