David S. Eisenberg

Reducing fibrous aggregates of protein tau is a possible strategy for halting progression of Alzheimer's dis-ease (AD). Previously we found that in vitro the D-peptide D-TLKIVWC disassembles tau fibrils from AD brains (AD-tau) into benign segments with no energy source present beyond ambient thermal agitation. This disassembly by a short peptide was unexpected, given that AD-tau is sufficiently stable to withstand disas-sembly in boiling SDS detergent. To consider D peptide-mediated disassembly as a potential therapeutic for AD, it is essential to understand the mechanism and energy source of the disassembly action. We find as-sembly of D-peptides into amyloid-like fibrils is essential for tau fibril disassembly. Cryo-EM and atomic force microscopy reveal that these D-peptide fibrils have a right-handed twist and embrace tau fibrils which have a left-handed twist. In binding to the AD-tau fibril, the oppositely twisted D-peptide fibril produces a strain, which is relieved by disassembly of both fibrils. This strain-relief mechanism appears to operate in other examples of amyloid fibril disassembly and provides a new direction for the development of first-in-class therapeutics for amyloid diseases.

Amyloid fibrils of tau are increasingly accepted as a cause of neuronal death and brain atrophy in Alzheimer’s disease (AD). Diminishing tau aggregation is a promising strategy in the search for efficacious AD therapeutics. Previously, our laboratory designed a six-residue, nonnatural amino acid inhibitor D-TLKIVW peptide (6-DP), which can prevent tau aggregation in vitro. However, it cannot block cell-to-cell transmission of tau aggregation. Here, we find D-TLKIVWC (7-DP), a d-cysteine extension of 6-DP, not only prevents tau aggregation but also fragments tau fibrils extracted from AD brains to neutralize their seeding ability and protect neuronal cells from tau-induced toxicity. To facilitate the transport of 7-DP across the blood-brain barrier, we conjugated it to magnetic nanoparticles (MNPs). The MNPs-DP complex retains the inhibition and fragmentation properties of 7-DP alone. Ten weeks of MNPs-DP treatment …

Heterogeneous nuclear ribonucleoprotein A2 (hnRNPA2) is a human ribonucleoprotein that transports RNA to designated locations for translation via its ability to phase separate. Its mutated form, D290V, is implicated in multisystem proteinopathy known to afflict two families, mainly with myopathy and Paget's disease of bone. Here, we investigate this mutant form of hnRNPA2 by determining cryo-EM structures of the recombinant D290V low complexity domain. We find that the mutant form of hnRNPA2 differs from the WT fibrils in four ways. In contrast to the WT fibrils, the PY-nuclear localization signals in the fibril cores of all three mutant polymorphs are less accessible to chaperones. Also, the mutant fibrils are more stable than WT fibrils as judged by phase separation, thermal stability, and energetic calculations. Similar to other pathogenic amyloids, the mutant fibrils are polymorphic. Thus, these structures offer …

ATTR amyloidosis is caused by the deposition of transthyretin in the form of amyloid fibrils in virtually every organ of the body, including the heart. This systemic deposition leads to a phenotypic variability that has not been molecularly explained yet. In brain amyloid conditions, previous studies suggest an association between clinical phenotype and the molecular structures of their amyloid fibrils. Here we investigate whether there is such an association in ATTRv amyloidosis patients carrying the mutation I84S. Using cryo-electron microscopy, we determined the structures of cardiac fibrils extracted from three ATTR amyloidosis patients carrying the ATTRv-I84S mutation, associated with a consistent clinical phenotype. We found that in each ATTRv-I84S patient, the cardiac fibrils exhibited different local conformations, and these variations can co-exist within the same fibril. Our finding suggests that one amyloid …

This invention relates to inhibitory peptides which bind to α-synuclein molecules and inhibit α-synuclein amyloidogenic aggregation, α-synuclein cytotoxicity, and spread of α-synuclein. Methods of making and using the inhibitory peptides (eg to treat subjects having conditions or diseases that are mediated by α-synuclein, such as Parkinson's disease, dementia with Lewy bodies, or MSA) are described.

Monocytes comprise two major subsets, Ly6C hi classical monocytes and Ly6C lo nonclassical monocytes. Notch2 signaling in Ly6C hi monocytes triggers transition to Ly6C lo monocytes, which require Nr4a1, Bcl6, Irf2, and Cebpb. By comparison, less is known...

Full wwPDB X-ray Structure Validation Report i Page 1 Full wwPDB X-ray Structure Validation Report i O Feb 27, 2014 – 02:08 PM GMT PDB ID : 3MI0 Title : Crystal Structure of Mycobacterium Tuberculosis Proteasome at 2.2 A Authors : Li, D.; Li, H. Deposited on : 2010-04-09 Resolution : 2.20 Å(reported) This is a full wwPDB validation report for a publicly released PDB entry. We welcome your comments at validation@mail.wwpdb.org A user guide is available at http://wwpdb.org/ValidationPDFNotes.html The following versions of software and data (see references) were used in the production of this report: MolProbity : 4.02b-467 Mogul : 1.15 2013 Xtriage (Phenix) : dev-1323 EDS : stable22639 Percentile statistics : 21963 Refmac : 5.8.0049 CCP4 : 6.3.0 (Settle) Ideal geometry (proteins) : Engh & Huber (2001) Ideal geometry (DNA, RNA) : Parkinson et. al. (1996) Validation Pipeline (wwPDB-VP) : stable22683 Page …

J-domain protein (JDP) molecular chaperones have emerged as central players that maintain a healthy proteome. The diverse members of the JDP family function as monomers/dimers and a small subset assemble into micron-sized oligomers. The oligomeric JDP members have eluded structural characterization due to their low-complexity, intrinsically disordered middle domains. This in turn, obscures the biological significance of these larger oligomers in protein folding processes. Here, we identified a short, aromatic motif within DNAJB8, that drives self-assembly through ν-ν stacking and determined its X-ray structure. We show that mutations in the motif disrupt DNAJB8 oligomerization in vitro and in cells. DNAJB8 variants that are unable to assemble bind to misfolded tau seeds more specifically and retain capacity to reduce protein aggregation in vitro and in cells. We propose a new model for DNAJB8 function in which the sequences in the low-complexity domains play distinct roles in assembly and substrate activity.HIGHLIGHTSDNAJB8 oligomerization is mediated by a short phenylalanine-based motif in the S/T domainMutation of a single phenylalanine yields a monomeric form of DNAJB8Monomeric DNABJ8 binds to an aggregation-prone substrateMonomeric DNAJB8 retains substrate aggregation prevention activity