Proteolytically active streptococcal pyrogenic exotoxin B cleaves monocytic cell urokinase receptor and releases an active fragment of the receptor from the cell surface

Beni B. Wolf, Catherine A. Gibson, Vivek Kapur, Isa M. Hussaini, James M. Musser, Steven L. Gonias

Research output: Contribution to journalArticle

43 Scopus citations

Abstract

Urokinase plasminogen activator (u-PA) receptor (u-PAR) is a glycosyl- phosphatidylinositol-anchored membrane protein that promotes pericellular proteolysis and cellular migration. This investigation demonstrates that u- PAR is a substrate for the proteolytically active form of streptococcal pyrogenic exotoxin B (SPE B), a potent virulence factor secreted by Streptococcus pyogenes. Treatment of U937 monocyte-like cells with SPE B decreased specific 125I-labeled single-chain u-PA binding by up to 85%. Cysteine proteinase inhibitors neutralized SPE B without affecting the activity of phosphatidylinositol-specific phospholipase C. Due to decreased u-PA binding, SPE B-treated U937 cells expressed decreased activity against a u-PA-specific fluorogenic substrate and plasminogen. SPE B released single- chain u-PA that was noncovalently bound to U937 cells or cross-linked to cellular receptors with bis(sulfo-succinimidyl) suberate. The mass of the released u-PA-receptor complex was 100 kDa. Western blot analysis confirmed that the u-PA receptor that was cleaved by SPE B is u-PAR. After deglycosylation, the mass of SPE B-released u-PAR was 35 kDa, slightly smaller than the phosphatidylinositol-specific phospholipase C-derived form of this receptor. SPE B-released u-PAR retained the ability to bind u-PA, as determined by u-PA affinity chromatography. We conclude that SPE B may inhibit u-PA binding to monocytic cells by at least two mechanisms: (i) by decreasing the level of functional cell surface u-PAR and (ii) by releasing a soluble form of u-PAR that competes with the cellular receptor for ligand.

Original languageEnglish (US)
Pages (from-to)30682-30687
Number of pages6
JournalJournal of Biological Chemistry
Volume269
Issue number48
StatePublished - Dec 2 1994

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Fingerprint Dive into the research topics of 'Proteolytically active streptococcal pyrogenic exotoxin B cleaves monocytic cell urokinase receptor and releases an active fragment of the receptor from the cell surface'. Together they form a unique fingerprint.

Cite this