Molecule of the Month: Amyloids
Alzheimer's disease and prion diseases are linked to unnatural aggregation of proteins into amyloid fibrils.
Amyloids and Disease
Exploring the Structure
Beta-Amyloid Fibrils (PDB entries 2lmn and 2lmp)
Another aspect of amyloids has also made them difficult to study: they are often highly polymorphic, forming many different types of fibrils. Two structures of amyloid-beta fibrils are shown here (PDB entries 2lmn and 2lmp ), with the peptide forming a two-fold and a three-fold fibril. Both have very similar interactions when the chains stack into the long beta sheet, but the lateral interactions between chains are different. To explore these structures in more detail, click on the image for an interactive JSmol.
Topics for Further Discussion
- You can use the Protein Feature View of amyloid-beta precursor protein to see how the fibril-forming portions fit into the entire protein sequence. Look for the label "Beta-a" in the "Molecular Processing" section to find the segment that forms the fibril.
- The beta strands in amyloid fibrils associate in many different ways, sometimes forming fibrils where the neighboring beta strands are parallel, and sometimes forming fibrils where neighboring strands have opposite orientations. For instance, compare PDB entries 2lmn and 2lnq, and use a cartoon representation to display the direction of the beta strands.
September 2015, David Goodsellhttp://doi.org/10.2210/rcsb_pdb/mom_2015_9