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The cysteine 34 residue of A1M/α1-microglobulin is essential for protection of irradiated cell cultures and reduction of carbonyl groups.

Rutardottir, Sigurbjörg LU ; Nilsson, E J C ; Pallon, Jan LU ; Gram, Magnus LU and Åkerström, Bo LU (2013) In Free Radical Research 47(6-7). p.541-550
Abstract
α1-microglobulin (A1M) is a 26 kDa plasma and a tissue protein belonging to the lipocalin family. The reductase and free radical scavenger A1M has been shown to protect cells and extracellular matrix against oxidative and irradiation-induced damage. The reductase activity was previously shown to depend upon an unpaired cysteinyl side-chain, C34, and three lysyl side-chains, K92, 118, and 130, located around the open end of the lipocalin pocket. The aim of this work was to investigate whether the cell and matrix protection by A1M is a result of its reductase activity by using A1M-variants with site-directed mutations of the C34, K92, K118, and K130 positions. The results show that the C34 side-chain is an absolute requirement for protection... (More)
α1-microglobulin (A1M) is a 26 kDa plasma and a tissue protein belonging to the lipocalin family. The reductase and free radical scavenger A1M has been shown to protect cells and extracellular matrix against oxidative and irradiation-induced damage. The reductase activity was previously shown to depend upon an unpaired cysteinyl side-chain, C34, and three lysyl side-chains, K92, 118, and 130, located around the open end of the lipocalin pocket. The aim of this work was to investigate whether the cell and matrix protection by A1M is a result of its reductase activity by using A1M-variants with site-directed mutations of the C34, K92, K118, and K130 positions. The results show that the C34 side-chain is an absolute requirement for protection of HepG2 cell cultures against alpha-particle irradiation-induced cell death, upregulation of stress response and cell cycle regulation genes. Mutation of C34 also resulted in loss of the reduction capacity toward heme- and hydrogen peroxide-oxidized collagen, and the radical species 2,2´-azino-bis (3-ethyl-benzo-thiazoline-6-sulphonic acid) (ABTS). Furthermore, mutation of C34 significantly suppressed the cell-uptake of A1M. The K92, K118, and K130 side-chains were of minor importance in cell protection and reduction of oxidized collagen but strongly influenced the reduction of the ABTS-radical. It is concluded that antioxidative protection of cells and collagen by A1M is totally dependent on its C34 amino acid residue. A model of the cell protection mechanism of A1M should be based on the redox activity of the free thiolyl group of the C34 side-chain and a regulatory role of the K92, K118, and K130 residues. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Free Radical Research
volume
47
issue
6-7
pages
541 - 550
publisher
Harwood Academic
external identifiers
  • wos:000319945700012
  • pmid:23642167
  • scopus:84878883367
  • pmid:23642167
ISSN
1029-2470
DOI
10.3109/10715762.2013.801555
language
English
LU publication?
yes
additional info
The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Division of Infection Medicine (BMC) (013024020), Nuclear Physics (Faculty of Technology) (011013007)
id
970502f3-d366-4061-a2cc-73c3bf56f148 (old id 3804933)
alternative location
http://www.ncbi.nlm.nih.gov/pubmed/23642167?dopt=Abstract
date added to LUP
2016-04-01 10:00:38
date last changed
2020-01-05 04:06:30
@article{970502f3-d366-4061-a2cc-73c3bf56f148,
  abstract     = {α1-microglobulin (A1M) is a 26 kDa plasma and a tissue protein belonging to the lipocalin family. The reductase and free radical scavenger A1M has been shown to protect cells and extracellular matrix against oxidative and irradiation-induced damage. The reductase activity was previously shown to depend upon an unpaired cysteinyl side-chain, C34, and three lysyl side-chains, K92, 118, and 130, located around the open end of the lipocalin pocket. The aim of this work was to investigate whether the cell and matrix protection by A1M is a result of its reductase activity by using A1M-variants with site-directed mutations of the C34, K92, K118, and K130 positions. The results show that the C34 side-chain is an absolute requirement for protection of HepG2 cell cultures against alpha-particle irradiation-induced cell death, upregulation of stress response and cell cycle regulation genes. Mutation of C34 also resulted in loss of the reduction capacity toward heme- and hydrogen peroxide-oxidized collagen, and the radical species 2,2´-azino-bis (3-ethyl-benzo-thiazoline-6-sulphonic acid) (ABTS). Furthermore, mutation of C34 significantly suppressed the cell-uptake of A1M. The K92, K118, and K130 side-chains were of minor importance in cell protection and reduction of oxidized collagen but strongly influenced the reduction of the ABTS-radical. It is concluded that antioxidative protection of cells and collagen by A1M is totally dependent on its C34 amino acid residue. A model of the cell protection mechanism of A1M should be based on the redox activity of the free thiolyl group of the C34 side-chain and a regulatory role of the K92, K118, and K130 residues.},
  author       = {Rutardottir, Sigurbjörg and Nilsson, E J C and Pallon, Jan and Gram, Magnus and Åkerström, Bo},
  issn         = {1029-2470},
  language     = {eng},
  number       = {6-7},
  pages        = {541--550},
  publisher    = {Harwood Academic},
  series       = {Free Radical Research},
  title        = {The cysteine 34 residue of A1M/α1-microglobulin is essential for protection of irradiated cell cultures and reduction of carbonyl groups.},
  url          = {https://lup.lub.lu.se/search/ws/files/1476541/4178758.pdf},
  doi          = {10.3109/10715762.2013.801555},
  volume       = {47},
  year         = {2013},
}