An inhibitory antibody blocks the first step in the dithiol/disulfide relay mechanism of the enzyme QSOX1

Iris Grossman, Assaf Alon, Tal Ilani, Deborah Fass

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

Quiescin sulfhydryl oxidase 1 (QSOX1) is a catalyst of disulfide bond formation that undergoes regulated secretion from fibroblasts and is over-produced in adenocarcinomas and other cancers. We have recently shown that QSOX1 is required for incorporation of particular laminin isoforms into the extracellular matrix (ECM) of cultured fibroblasts and, as a consequence, for tumor cell adhesion to and penetration of the ECM. The known role of laminins in integrin-mediated cell survival and motility suggests that controlling QSOX1 activity may provide a novel means of combating metastatic disease. With this motivation, we developed a monoclonal antibody that inhibits the activity of human QSOX1. Here, we present the biochemical and structural characterization of this antibody and demonstrate that it is a tight-binding inhibitor that blocks one of the redox-active sites in the enzyme, but not the site at which de novo disulfides are generated catalytically. Sulfhydryl oxidase activity is thus prevented without direct binding of the sulfhydryl oxidase domain, confirming the model for the interdomain QSOX1 electron transfer mechanism originally surmised based on mutagenesis and protein dissection. In addition, we developed a single-chain variant of the antibody and show that it is a potent QSOX1 inhibitor. The QSOX1 inhibitory antibody will be a valuable tool in studying the role of ECM composition and architecture in cell migration, and the recombinant version may be further developed for potential therapeutic applications based on manipulation of the tumor microenvironment.

Original languageEnglish
Pages (from-to)4366-4378
Number of pages13
JournalJournal of Molecular Biology
Volume425
Issue number22
DOIs
StatePublished - 15 Nov 2013
Externally publishedYes

Keywords

  • anti-metastatic drugs
  • disulfide bonds
  • extracellular matrix
  • laminin
  • monoclonal antibody

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Molecular Biology

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