Biology subjects

Rau, M. J.

Publications and source records attributed to Rau, M. J..

4 recordsLinked to original sources

bioRxiv2023

Structure of alpha-synuclein fibrils derived from human Lewy body dementia tissue

The defining feature of Parkinson disease (PD) and Lewy body dementia (LBD) is the accumulation of alpha-synuclein (Asyn) fibrils in Lewy bodies and Lewy neurites. We developed and validated a novel method to amplify Asyn fibrils extracted from LBD postmortem tissue samples and used solid state nuclear magnetic resonance (SSNMR) studies to determine atomic resolution structure. Amplified LBD Asyn fibrils comprise two protofilaments with pseudo-21 helical screw symmetry, very low twist and an interface formed by antiparallel beta strands of residues 85-93. The fold is highly similar to the fold determined by a recent cryo-electron microscopy study for a minority population of twisted single protofilament fibrils extracted from LBD tissue. These results expand the structural landscape of LBD Asyn fibrils and inform further studies of disease mechanisms, imaging agents and therapeutics targeting Asyn.

neuroscience↗

bioRxiv2022

Lipid nanodisc scaffold and size alters the structure of a pentameric ligand-gated ion channel

Lipid nanodiscs have become the standard reconstitution system for structural and biochemical studies of membrane proteins, especially using single particle cryo-EM. We find that reconstitution of the pentameric ligand-gated ion channel (pLGIC), Erwinia ligand-gated ion channel (ELIC), in different nanodisc scaffolds (MSP1E3D1, SMA, saposin, spMSP1D1) produces distinct apo and agonist-bound structures. In the presence of agonist, different nanodiscs scaffolds produce concerted conformational changes associated with activation in ELIC, with larger nanodiscs showing more activated conformations. The effect of different nanodisc scaffolds on ELIC structure extends to the extracellular domain and agonist binding site. Molecular dynamic simulations of ELIC in small and large nanodiscs suggest that the impact of the nanodisc on ELIC structure is influenced by nanodisc size. Overall, the results indicate that the nanodisc profoundly affects the structure of a pLGIC, and suggest that larger circularized nanodiscs may be advantageous to approximate a lipid membrane environment.

biophysics↗

bioRxiv2021

Myopathy mutations in DNAJB6 slow conformer specific substrate processing that is rescued by NEF modulation

Molecular chaperones, or heat shock proteins (HSPs), protect against the toxic misfolding and aggregation of proteins. As such, mutations or deficiencies within the chaperone network can lead to disease. In fact, dominant mutations in DNAJB6 (Hsp40/Sis1), an Hsp70 co-chaperone, leads to a protein aggregate myopathy termed Limb-Girdle Muscular Dystrophy Type D1 (LGMDD1). DNAJB6 client proteins and co-chaperone interactions in skeletal muscle are not known. Here, we used the yeast prion model client in conjunction with in vitro chaperone activity assays to gain mechanistic insights, and found that LGMDD1 mutants affect Hsp40 functions. Strikingly, the mutants changed the structure of client protein aggregates, as determined by altered distribution of prion strains. They also impair the Hsp70 ATPase cycle, dimerization, and substrate processing and consequently poison the function of wild-type protein. These results define the mechanisms by which LGMDD1 mutations alter chaperone activity and provide avenues for therapeutic intervention.

biochemistry↗

bioRxiv2020

Cryo-EM structure of a proton-activated chloride channel TMEM206

TMEM206 has been recently identified as an evolutionarily conserved chloride channel that underlies ubiquitously expressed, proton-activated, outwardly rectifying anion currents. Here we report the cryo-electron microscopy structure of pufferfish TMEM206, which forms a trimeric channel, with each subunit comprising two transmembrane segments, the outer and inner helices, and a large extracellular domain. An ample vestibule in the extracellular region is accessible laterally from the three side portals. The central pore contains multiple constrictions preventing ion conduction. A conserved lysine residue near the cytoplasmic end of the inner helix forms the presumed chloride ion selectivity filter. Unprecedentedly, the core structure and assembly closely resemble those of the epithelial sodium channel/degenerin family of sodium channels that are unrelated in amino acid sequence and conduct cations instead of anions. Together with electrophysiology, this work provides insights into ion conduction and gating for a new class of chloride channels that is architecturally distinct from previously characterized chloride channel families.

biophysics↗