Tau Aggregation Propensity Engrained in Its Solution State.
A peptide fragment of the human tau protein which stacks to form neat cross β-sheet fibrils, resembling that found in pathological aggregation, (273)GKVQIINKKLDL(284) (here "R2/WT"), was modified with a spin-label at the N-terminus. With the resulting peptide, R2/G273C-SL, we probed events at time scales spanning seconds to hours after aggregation is initiated using transmission electron microscopy (TEM), thioflavin T (THT) fluorescence, ion mobility mass spectrometry (IMMS), electron paramagnetic resonance (EPR), and Overhauser dynamic nuclear polarization (ODNP) to determine if deliberate changes to its conformational states and population in solution influence downstream propensity to form fibrillar aggregates. We find varying solution conditions by adding the osmolyte urea or TMAO, or simply using different buffers (acetate buffer, phosphate buffer, or water), produces significant differences in early monomer/dimer populations and conformations. Crucially, these characteristics of the peptide in solution state before aggregation is initiated dictate the fibril formation propensity after aggregation. We conclude the driving forces that accelerate aggregation, when heparin is added, do not override the subtle intra- or interprotein interactions induced by the initial solvent conditions. In other words, the balance of protein-protein vs protein-solvent interactions present in the initial solution conditions is a critical driving force for fibril formation.
Department of Chemistry and Biochemistry and ‡Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California at Santa Barbara , Santa Barbara, California 93106, United States.
Neil A
NA
Eschmann
Department of Chemistry and Biochemistry and ‡Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California at Santa Barbara , Santa Barbara, California 93106, United States.
Thanh D
TD
Do
Department of Chemistry and Biochemistry and ‡Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California at Santa Barbara , Santa Barbara, California 93106, United States.
Nichole E
NE
LaPointe
Department of Chemistry and Biochemistry and ‡Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California at Santa Barbara , Santa Barbara, California 93106, United States.
Joan-Emma
JE
Shea
Department of Chemistry and Biochemistry and ‡Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California at Santa Barbara , Santa Barbara, California 93106, United States.
Stuart C
SC
Feinstein
Department of Chemistry and Biochemistry and ‡Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California at Santa Barbara , Santa Barbara, California 93106, United States.
Michael T
MT
Bowers
Department of Chemistry and Biochemistry and ‡Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California at Santa Barbara , Santa Barbara, California 93106, United States.
Songi
S
Han
D000595:Amino Acid Sequence; D052160:Benzothiazoles; D004578:Electron Spin Resonance Spectroscopy; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D012996:Solutions; D021241:Spectrometry, Mass, Electrospray Ionization; D013844:Thiazoles / Q000737:chemistry; D016875:tau Proteins / Q000737:chemistry*
D052160:Benzothiazoles; D012996:Solutions; D013844:Thiazoles; D016875:tau Proteins; C009462:thioflavin T