"Structural characterization of the minimal segment of TDP-43 competent for aggregation".
TDP-43 is a nuclear protein whose abnormal aggregates are implicated in ALS and FTLD. Recently, an Asn/Gln rich C-terminal segment of TDP-43 has been shown to produce aggregation in vitro and reproduce most of the protein's pathological hallmarks in cells, but little is known about this segment's structure. Here, CD and 2D heteronuclear NMR spectroscopies provide evidence that peptides corresponding to the wild type and mutated sequences of this segment adopt chiefly disordered conformations that, in the case of the wild type sequence, spontaneously forms a β-sheet rich oligomer. Moreover, MD simulation provides evidence for a structure consisting of two β-strands and a well-defined, yet non-canonical structural element. Furthermore, MD simulations of four pathological mutations (Q343R, N345K, G348V and N352S) occurring in this segment predict that all of them could affect this region's structure. In particular, the Q343R variant tends to stabilize disordered conformers, N345K permits the formation of longer, more stable β-strands, and G348V tends to shorten and destabilize them. Finally, N352S acts to alter the β-stand register and when S352 is phosphorylated, it induces partial unfolding. Our results provide a better understanding of TDP-43 aggregation process and will be useful to design effectors capable to modulate its progression.
Instituto de Química Física "Rocasolano" CSIC, Serrano 119, E-28006 Madrid, Spain.
Miguel
M
Mompeán
International Centre for Genetic Engineering and Biotechnology, I-34149 Trieste, Italy.
Emanuele
E
Buratti
International Centre for Genetic Engineering and Biotechnology, I-34149 Trieste, Italy.
Corrado
C
Guarnaccia
Chemistry Dept., Faculty of Science and Technology & Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.
Rui M M
RM
Brito
Dept. of Biochemistry, University of Toronto, Toronto Medical Discovery Tower 4-305, MaRS Centre, 101 College St., Toronto, ON M5G 1L7, Canada.
Avijit
A
Chakrabartty
International Centre for Genetic Engineering and Biotechnology, I-34149 Trieste, Italy. Electronic address: baralle@icgeb.org.
Francisco E
FE
Baralle
Instituto de Química Física "Rocasolano" CSIC, Serrano 119, E-28006 Madrid, Spain. Electronic address: dlaurents@iqfr.csic.es.
Douglas V
DV
Laurents
D000595:Amino Acid Sequence; D000690:Amyotrophic Lateral Sclerosis / Q000235:genetics; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics*; D006801:Humans; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D010766:Phosphorylation; D017354:Point Mutation; D011487:Protein Conformation; D055550:Protein Stability; D017433:Protein Structure, Secondary
D004268:DNA-Binding Proteins
Amyotrophic lateral sclerosis (ALS); Circular dichroism; Frontotemportal lobar degeneration (FTLD); Molecular dynamics; NMR; Protein misfolding & aggregation