The C-terminal proteolytic processing of extracellular superoxide dismutase is redox regulated.

Published

Journal Article

The antioxidant protein extracellular superoxide dismutase (EC-SOD) encompasses a C-terminal region that mediates interactions with a number of ligands in the extracellular matrix (ECM). This ECM-binding region can be removed by limited proteolysis before secretion, thus supporting the formation of EC-SOD tetramers with variable binding capacity. The ECM-binding region contains a cysteine residue (Cys219) that is known to be involved in an intersubunit disulfide bridge. We have determined the redox potential of this disulfide bridge and show that both EC-SOD dimers and EC-SOD monomers are present within the intracellular space. The proteolytic processing of the ECM-binding region in vitro was modulated by the redox status of Cys219, allowing cleavage under reducing conditions only. When wild-type EC-SOD or the monomeric variant Cys219Ser was expressed in mammalian cells proteolysis did not occur. However, when cells were exposed to oxidative stress conditions, proteolytic processing was observed for wild-type EC-SOD but not for the Cys219Ser variant. Although the cellular response to oxidative stress is complex, our data suggest that proteolytic removal of the ECM-binding region is regulated by the intracellular generation of an EC-SOD monomer and that Cys219 plays an important role as a redox switch allowing the cellular machinery to secrete cleaved EC-SOD.

Full Text

Cited Authors

  • Gottfredsen, RH; Tran, SM-H; Larsen, UG; Madsen, P; Nielsen, MS; Enghild, JJ; Petersen, SV

Published Date

  • January 2012

Published In

Volume / Issue

  • 52 / 1

Start / End Page

  • 191 - 197

PubMed ID

  • 22062630

Pubmed Central ID

  • 22062630

Electronic International Standard Serial Number (EISSN)

  • 1873-4596

International Standard Serial Number (ISSN)

  • 0891-5849

Digital Object Identifier (DOI)

  • 10.1016/j.freeradbiomed.2011.10.443

Language

  • eng