Subtilase cytotoxin cleaves newly synthesized BiP and blocks antibody secretion in B lymphocytes

Chih Chi Andrew Hu, Stephanie K. Dougan, Sebastian Virreira Winter, Adrienne W. Paton, James C. Paton, Hidde L. Ploegh

Research output: Contribution to journalArticle

28 Scopus citations

Abstract

Shiga-toxigenic Escherichia coli (STEC) use subtilase cytotoxin (SubAB) to interfere with adaptive immunity. Its inhibition of immunoglobulin secretion is both rapid and profound. SubAB favors cleavage of the newly synthesized immunoglobulin heavy chain-binding protein (BiP) to yield a C-terminal fragment that contains BiP's substrate-binding domain. In the absence of its regulatory nucleotide-binding domain, the SubAB-cleaved C-terminal BiP fragment remains tightly bound to newly synthesized immunoglobulin light chains, resulting in retention of light chains in the endoplasmic reticulum (ER). Immunoglobulins are thus detained in the ER, making impossible the secretion of antibodies by SubABtreated B cells. The inhibitory effect of SubAB is highly specific for antibody secretion, because other secretory proteins such as IL-6 are released normally from SubAB-treated B cells. Although SubAB also causes BiP cleavage in HepG2 hepatoma cells, (glyco)protein secretion continues unabated in SubAB-exposed HepG2 cells. This specific block in antibody secretion is a novel means of immune evasion for STEC. The differential cleavage of newly synthesized versus "aged" BiP by SubAB in the ER provides insight into the architecture of the ER compartments involved.

Original languageEnglish (US)
Pages (from-to)2429-2440
Number of pages12
JournalJournal of Experimental Medicine
Volume206
Issue number11
DOIs
StatePublished - Oct 26 2009

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

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