Parkinsons disease has long been known to involve the loss of dopaminergic neurons in the substantia nigra and the coincidental appearance of Lewy bodies containing oligomerized forms of alpha-synuclein. The catecholaldehyde hypothesis posits a causal link between these two central pathologies mediated by 3,4-dihydroxyphenylacetaldehyde (DOPAL), the most toxic dopamine metabolite. We have determined the structure of the dominant product formed in reactions between DOPAL and synuclein, a dicatechol pyrrole lysine adduct. This novel modification results from the addition of two DOPAL molecules to the Lys sidechain amine through their aldehyde moieties and the formation of a new carbon-carbon bond between their alkyl chains to generate a pyrrole ring. The product, dicatechol-pyrrole-lysine (DCPL), is the only detectable adduct at low concentrations of DOPAL, and therefore is likely to play a key role in DOPAL-induced crosslinking of alpha-synuclein. Our study of the chemistry that leads to cross-linking of DCPL-modified alpha-synuclein proteins showed that autoxidation of DCPL's catechol rings spurs its decomposition, yielding an intermediate dicatechol isoindole lysine (DCIL) product formed by an intramolecular reaction of the two catechol rings to give an unstable tetracyclic structure. DCIL then reacts with a second DCIL to give a dimeric, di-DCIL. This product is formed by an intermolecular carbon-carbon bond between the isoindole rings of the two DCILs that generates two structurally nonequivalent and separable atropisomers. Using alpha-synuclein, we demonstrated that the DOPAL-catalyzed formation of oligomers can be separated into two steps. The initial adduct formation occurs robustly within an hour, with DCPL as the main product, and the second step cross-links alpha-synuclein molecules. Exploiting this two-stage reaction, we used an isotopic labeling approach to show the predominant cross-linking mechanism is an interadduct reaction. We confirmed by mass spectrometry that a mass consistent with a di-DCIL linkage can be observed in a DOPAL-generated dimeric alpha-synuclein . Our work elucidates previously unknown pathways of catechol-based oxidative protein damage and should facilitate efforts to detect DOPAL-based cross-links in disease-state neurons.

Project Start
Project End
Budget Start
Budget End
Support Year
12
Fiscal Year
2018
Total Cost
Indirect Cost
Name
U.S. National Inst Diabetes/Digst/Kidney
Department
Type
DUNS #
City
State
Country
Zip Code
Shen, Yang; Roche, Julien; Grishaev, Alexander et al. (2018) Prediction of nearest neighbor effects on backbone torsion angles and NMR scalar coupling constants in disordered proteins. Protein Sci 27:146-158
Werner-Allen, Jonathan W; Monti, Sarah; DuMond, Jenna F et al. (2018) Isoindole Linkages Provide a Pathway for DOPAL-Mediated Cross-Linking of ?-Synuclein. Biochemistry 57:1462-1474
Alderson, T Reid; Lee, Jung Ho; Charlier, Cyril et al. (2018) Propensity for cis-Proline Formation in Unfolded Proteins. Chembiochem 19:37-42
Stolzenberg, Ethan; Berry, Deborah; Yang, De et al. (2017) A Role for Neuronal Alpha-Synuclein in Gastrointestinal Immunity. J Innate Immun 9:456-463
Perni, Michele; Galvagnion, CĂ©line; Maltsev, Alexander et al. (2017) A natural product inhibits the initiation of ?-synuclein aggregation and suppresses its toxicity. Proc Natl Acad Sci U S A 114:E1009-E1017
Werner-Allen, Jon W; Levine, Rodney L; Bax, Ad (2017) Superoxide is the critical driver of DOPAL autoxidation, lysyl adduct formation, and crosslinking of ?-synuclein. Biochem Biophys Res Commun 487:281-286
Roche, Julien; Ying, Jinfa; Bax, Ad (2016) Accurate measurement of (3)J(HNH?) couplings in small or disordered proteins from WATERGATE-optimized TROSY spectra. J Biomol NMR 64:1-7
Alderson, T Reid; Bax, Ad (2016) Parkinson's disease: Disorder in the court. Nature 530:38-9
Werner-Allen, Jon W; DuMond, Jenna F; Levine, Rodney L et al. (2016) Toxic Dopamine Metabolite DOPAL Forms an Unexpected Dicatechol Pyrrole Adduct with Lysines of ?-Synuclein. Angew Chem Int Ed Engl 55:7374-8
Lee, Jung Ho; Ying, Jinfa; Bax, Ad (2016) Quantitative evaluation of positive ? angle propensity in flexible regions of proteins from three-bond J couplings. Phys Chem Chem Phys 18:5759-70

Showing the most recent 10 out of 22 publications