Charge Regulation during Amyloid Formation of α-Synuclein
Pálmadóttir, Tinna LU ; Malmendal, Anders LU ; Leiding, Thom LU ; Lund, Mikael LU
and Linse, Sara
LU
(2021)
In Journal of the American Chemical Society
143(20).
p.7777-7791
- Abstract
Electrostatic interactions play crucial roles in protein function. Measuring pKa value perturbations upon complex formation or self-assembly of e.g. amyloid fibrils gives valuable information about the effect of electrostatic interactions in those processes. Site-specific pKa value determination by solution NMR spectroscopy is challenged by the high molecular weight of amyloid fibrils. Here we report a pH increase during fibril formation of α-synuclein, observed using three complementary experimental methods: pH electrode measurements in water; colorimetric changes of a fluorescent indicator; and chemical shift changes for histidine residues using solution state NMR spectroscopy. A significant pH... (More)
Electrostatic interactions play crucial roles in protein function. Measuring pKa value perturbations upon complex formation or self-assembly of e.g. amyloid fibrils gives valuable information about the effect of electrostatic interactions in those processes. Site-specific pKa value determination by solution NMR spectroscopy is challenged by the high molecular weight of amyloid fibrils. Here we report a pH increase during fibril formation of α-synuclein, observed using three complementary experimental methods: pH electrode measurements in water; colorimetric changes of a fluorescent indicator; and chemical shift changes for histidine residues using solution state NMR spectroscopy. A significant pH increase was detected during fibril formation in water, on average by 0.9 pH units from 5.6 to 6.5, showing that protons are taken up during fibril formation. The pH upshift was used to calculate the average change in the apparent pKaave value of the acidic residues, which was found to increase by at least 1.1 unit due to fibril formation. Metropolis Monte Carlo simulations were performed on a comparable system that also showed a proton uptake due to fibril formation. Fibril formation moreover leads to a significant change in proton binding capacitance. Parallel studies of a mutant with five charge deletions in the C-terminal tail revealed a smaller pH increase due to fibril formation, and a smaller change (0.5 units on average) in the apparent pKaave values of the acidic residues. We conclude that the proton uptake during the fibril formation is connected to the high density of acidic residues in the C-terminal tail of α-synuclein.
(Less)
- author
- Pálmadóttir, Tinna
LU
; Malmendal, Anders
LU
; Leiding, Thom
LU
; Lund, Mikael
LU
and Linse, Sara
LU
- organization
- publishing date
- 2021-05-26
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Nanofibers, Peptides and proteins, Monomers, Fluorescence, pH
- in
- Journal of the American Chemical Society
- volume
- 143
- issue
- 20
- pages
- 15 pages
- publisher
- The American Chemical Society (ACS)
- external identifiers
-
- pmid:33998793
- scopus:85107081818
- ISSN
- 0002-7863
- DOI
- 10.1021/jacs.1c01925
- language
- English
- LU publication?
- yes
- additional info
- Publisher Copyright: © 2021 The Authors. Published by American Chemical Society.
- id
- d776dbfb-3904-46a1-b345-d56a5ba4c4d5
- date added to LUP
- 2021-11-12 13:05:18
- date last changed
- 2024-04-26 02:21:23
@article{d776dbfb-3904-46a1-b345-d56a5ba4c4d5,
abstract = {{<p>Electrostatic interactions play crucial roles in protein function. Measuring p<i>K</i><sub>a</sub> value perturbations upon complex formation or self-assembly of e.g. amyloid fibrils gives valuable information about the effect of electrostatic interactions in those processes. Site-specific p<i>K</i><sub>a</sub> value determination by solution NMR spectroscopy is challenged by the high molecular weight of amyloid fibrils. Here we report a pH increase during fibril formation of α-synuclein, observed using three complementary experimental methods: pH electrode measurements in water; colorimetric changes of a fluorescent indicator; and chemical shift changes for histidine residues using solution state NMR spectroscopy. A significant pH increase was detected during fibril formation in water, on average by 0.9 pH units from 5.6 to 6.5, showing that protons are taken up during fibril formation. The pH upshift was used to calculate the average change in the apparent p<i>K</i><sub>a</sub><sup>ave</sup> value of the acidic residues, which was found to increase by at least 1.1 unit due to fibril formation. Metropolis Monte Carlo simulations were performed on a comparable system that also showed a proton uptake due to fibril formation. Fibril formation moreover leads to a significant change in proton binding capacitance. Parallel studies of a mutant with five charge deletions in the C-terminal tail revealed a smaller pH increase due to fibril formation, and a smaller change (0.5 units on average) in the apparent p<i>K</i><sub>a</sub><sup>ave</sup> values of the acidic residues. We conclude that the proton uptake during the fibril formation is connected to the high density of acidic residues in the C-terminal tail of α-synuclein. </p>}},
author = {{Pálmadóttir, Tinna and Malmendal, Anders and Leiding, Thom and Lund, Mikael and Linse, Sara}},
issn = {{0002-7863}},
keywords = {{Nanofibers; Peptides and proteins; Monomers; Fluorescence; pH}},
language = {{eng}},
month = {{05}},
number = {{20}},
pages = {{7777--7791}},
publisher = {{The American Chemical Society (ACS)}},
series = {{Journal of the American Chemical Society}},
title = {{Charge Regulation during Amyloid Formation of α-Synuclein}},
url = {{http://dx.doi.org/10.1021/jacs.1c01925}},
doi = {{10.1021/jacs.1c01925}},
volume = {{143}},
year = {{2021}},
}