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SAXS and stability studies of iron-induced oligomers of bacterial frataxin CyaY

Fekry, Mostafa; Alshokry, Wessen ; Grela, Przemysław; Tchórzewski, Marek LU ; Ahlgren, Eva Christina LU ; Söderberg, Christopher A. LU ; Gakh, Oleksandr; Isaya, Grazia and Al-Karadaghi, Salam LU (2017) In PLoS ONE 12(9). p.0184961-0184961
Abstract

Frataxin is a highly conserved protein found in both prokaryotes and eukaryotes. It is involved in several central functions in cells, which include iron delivery to biochemical processes, such as heme synthesis, assembly of iron-sulfur clusters (ISC), storage of surplus iron in conditions of iron overload, and repair of ISC in aconitase. Frataxin from different organisms has been shown to undergo iron-dependent oligomerization. At least two different classes of oligomers, with different modes of oligomer packing and stabilization, have been identified. Here, we continue our efforts to explore the factors that control the oligomerization of frataxin from different organisms, and focus on E. coli frataxin CyaY. Using small-angle X-ray... (More)

Frataxin is a highly conserved protein found in both prokaryotes and eukaryotes. It is involved in several central functions in cells, which include iron delivery to biochemical processes, such as heme synthesis, assembly of iron-sulfur clusters (ISC), storage of surplus iron in conditions of iron overload, and repair of ISC in aconitase. Frataxin from different organisms has been shown to undergo iron-dependent oligomerization. At least two different classes of oligomers, with different modes of oligomer packing and stabilization, have been identified. Here, we continue our efforts to explore the factors that control the oligomerization of frataxin from different organisms, and focus on E. coli frataxin CyaY. Using small-angle X-ray scattering (SAXS), we show that higher iron-to-protein ratios lead to larger oligomeric species, and that oligomerization proceeds in a linear fashion as a results of iron oxidation. Native mass spectrometry and online size-exclusion chromatography combined with SAXS show that a dimer is the most common form of CyaY in the presence of iron at atmospheric conditions. Modeling of the dimer using the SAXS data confirms the earlier proposed head-to-tail packing arrangement of monomers. This packing mode brings several conserved acidic residues into close proximity to each other, creating an environment for metal ion binding and possibly even mineralization. Together with negative-stain electron microscopy, the experiments also show that trimers, tetramers, pentamers, and presumably higher-order oligomers may exist in solution. Nano-differential scanning fluorimetry shows that the oligomers have limited stability and may easily dissociate at elevated temperatures. The factors affecting the possible oligomerization mode are discussed.

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author
organization
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Contribution to journal
publication status
published
subject
in
PLoS ONE
volume
12
issue
9
pages
0184961 - 0184961
publisher
Public Library of Science
external identifiers
  • scopus:85031682361
  • wos:000411314700048
ISSN
1932-6203
DOI
10.1371/journal.pone.0184961
language
English
LU publication?
yes
id
6b8bbe9b-625f-43cb-bff2-372dd867b3dd
date added to LUP
2017-10-31 09:52:05
date last changed
2018-01-16 13:25:08
@article{6b8bbe9b-625f-43cb-bff2-372dd867b3dd,
  abstract     = {<p>Frataxin is a highly conserved protein found in both prokaryotes and eukaryotes. It is involved in several central functions in cells, which include iron delivery to biochemical processes, such as heme synthesis, assembly of iron-sulfur clusters (ISC), storage of surplus iron in conditions of iron overload, and repair of ISC in aconitase. Frataxin from different organisms has been shown to undergo iron-dependent oligomerization. At least two different classes of oligomers, with different modes of oligomer packing and stabilization, have been identified. Here, we continue our efforts to explore the factors that control the oligomerization of frataxin from different organisms, and focus on E. coli frataxin CyaY. Using small-angle X-ray scattering (SAXS), we show that higher iron-to-protein ratios lead to larger oligomeric species, and that oligomerization proceeds in a linear fashion as a results of iron oxidation. Native mass spectrometry and online size-exclusion chromatography combined with SAXS show that a dimer is the most common form of CyaY in the presence of iron at atmospheric conditions. Modeling of the dimer using the SAXS data confirms the earlier proposed head-to-tail packing arrangement of monomers. This packing mode brings several conserved acidic residues into close proximity to each other, creating an environment for metal ion binding and possibly even mineralization. Together with negative-stain electron microscopy, the experiments also show that trimers, tetramers, pentamers, and presumably higher-order oligomers may exist in solution. Nano-differential scanning fluorimetry shows that the oligomers have limited stability and may easily dissociate at elevated temperatures. The factors affecting the possible oligomerization mode are discussed.</p>},
  author       = {Fekry, Mostafa and Alshokry, Wessen  and Grela, Przemysław and Tchórzewski, Marek and Ahlgren, Eva Christina and Söderberg, Christopher A. and Gakh, Oleksandr and Isaya, Grazia and Al-Karadaghi, Salam},
  issn         = {1932-6203},
  language     = {eng},
  number       = {9},
  pages        = {0184961--0184961},
  publisher    = {Public Library of Science},
  series       = {PLoS ONE},
  title        = {SAXS and stability studies of iron-induced oligomers of bacterial frataxin CyaY},
  url          = {http://dx.doi.org/10.1371/journal.pone.0184961},
  volume       = {12},
  year         = {2017},
}