Instability of toxin A subunit of AB5 toxins in the bacterial periplasm caused by deficiency of their cognate B subunits

Sang Hyun Kim, Su Hyang Ryu, Sang Ho Lee, Yong Hoon Lee, Sang Rae Lee, Jae Won Huh, Sun Uk Kim, Ekyune Kim, Sunghyun Kim, Sangyong Jon, Russell E. Bishop, Kyu Tae Chang

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Shiga toxin (STx) belongs to the AB5 toxin family and is transiently localized in the periplasm before secretion into the extracellular milieu. While producing outer membrane vesicles (OMVs) containing only A subunit of the toxin (STxA), we created specific STx1B- and STx2B-deficient mutants of E. coli O157:H7. Surprisingly, STxA subunit was absent in the OMVs and periplasm of the STxB-deficient mutants. In parallel, the A subunit of heat-labile toxin (LT) of enterotoxigenic E. coli (ETEC) was absent in the periplasm of the LT-B-deficient mutant, suggesting that instability of toxin A subunit in the absence of the B subunit is a common phenomenon in the AB5 bacterial toxins. Moreover, STx2A was barely detectable in the periplasm of E. coli JM109 when stx2A was overexpressed alone, while it was stably present when stxB was co-expressed. Compared with STx2 holotoxin, purified STx2A was degraded rapidly by periplasmic proteases when assessed for in vitro proteolytic susceptibility, suggesting that the B subunit contributes to stability of the toxin A subunit in the periplasm. We propose a novel role for toxin B subunits of AB5 toxins in protection of the A subunit from proteolysis during holotoxin assembly in the periplasm.

Original languageEnglish
Pages (from-to)2359-2365
Number of pages7
JournalBiochimica et Biophysica Acta - Biomembranes
Volume1808
Issue number10
DOIs
Publication statusPublished - 2011 Oct 1
Externally publishedYes

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Bacterial Toxins
Periplasm
Escherichia coli
Proteolysis
Shiga Toxin
Membranes
Peptide Hydrolases
Enterotoxigenic Escherichia coli
Escherichia coli O157
Hot Temperature
stichoposide

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Biophysics

Cite this

Instability of toxin A subunit of AB5 toxins in the bacterial periplasm caused by deficiency of their cognate B subunits. / Kim, Sang Hyun; Ryu, Su Hyang; Lee, Sang Ho; Lee, Yong Hoon; Lee, Sang Rae; Huh, Jae Won; Kim, Sun Uk; Kim, Ekyune; Kim, Sunghyun; Jon, Sangyong; Bishop, Russell E.; Chang, Kyu Tae.

In: Biochimica et Biophysica Acta - Biomembranes, Vol. 1808, No. 10, 01.10.2011, p. 2359-2365.

Research output: Contribution to journalArticle

Kim, SH, Ryu, SH, Lee, SH, Lee, YH, Lee, SR, Huh, JW, Kim, SU, Kim, E, Kim, S, Jon, S, Bishop, RE & Chang, KT 2011, 'Instability of toxin A subunit of AB5 toxins in the bacterial periplasm caused by deficiency of their cognate B subunits', Biochimica et Biophysica Acta - Biomembranes, vol. 1808, no. 10, pp. 2359-2365. https://doi.org/10.1016/j.bbamem.2011.06.016
Kim, Sang Hyun ; Ryu, Su Hyang ; Lee, Sang Ho ; Lee, Yong Hoon ; Lee, Sang Rae ; Huh, Jae Won ; Kim, Sun Uk ; Kim, Ekyune ; Kim, Sunghyun ; Jon, Sangyong ; Bishop, Russell E. ; Chang, Kyu Tae. / Instability of toxin A subunit of AB5 toxins in the bacterial periplasm caused by deficiency of their cognate B subunits. In: Biochimica et Biophysica Acta - Biomembranes. 2011 ; Vol. 1808, No. 10. pp. 2359-2365.
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abstract = "Shiga toxin (STx) belongs to the AB5 toxin family and is transiently localized in the periplasm before secretion into the extracellular milieu. While producing outer membrane vesicles (OMVs) containing only A subunit of the toxin (STxA), we created specific STx1B- and STx2B-deficient mutants of E. coli O157:H7. Surprisingly, STxA subunit was absent in the OMVs and periplasm of the STxB-deficient mutants. In parallel, the A subunit of heat-labile toxin (LT) of enterotoxigenic E. coli (ETEC) was absent in the periplasm of the LT-B-deficient mutant, suggesting that instability of toxin A subunit in the absence of the B subunit is a common phenomenon in the AB5 bacterial toxins. Moreover, STx2A was barely detectable in the periplasm of E. coli JM109 when stx2A was overexpressed alone, while it was stably present when stxB was co-expressed. Compared with STx2 holotoxin, purified STx2A was degraded rapidly by periplasmic proteases when assessed for in vitro proteolytic susceptibility, suggesting that the B subunit contributes to stability of the toxin A subunit in the periplasm. We propose a novel role for toxin B subunits of AB5 toxins in protection of the A subunit from proteolysis during holotoxin assembly in the periplasm.",
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AU - Kim, Sang Hyun

AU - Ryu, Su Hyang

AU - Lee, Sang Ho

AU - Lee, Yong Hoon

AU - Lee, Sang Rae

AU - Huh, Jae Won

AU - Kim, Sun Uk

AU - Kim, Ekyune

AU - Kim, Sunghyun

AU - Jon, Sangyong

AU - Bishop, Russell E.

AU - Chang, Kyu Tae

PY - 2011/10/1

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N2 - Shiga toxin (STx) belongs to the AB5 toxin family and is transiently localized in the periplasm before secretion into the extracellular milieu. While producing outer membrane vesicles (OMVs) containing only A subunit of the toxin (STxA), we created specific STx1B- and STx2B-deficient mutants of E. coli O157:H7. Surprisingly, STxA subunit was absent in the OMVs and periplasm of the STxB-deficient mutants. In parallel, the A subunit of heat-labile toxin (LT) of enterotoxigenic E. coli (ETEC) was absent in the periplasm of the LT-B-deficient mutant, suggesting that instability of toxin A subunit in the absence of the B subunit is a common phenomenon in the AB5 bacterial toxins. Moreover, STx2A was barely detectable in the periplasm of E. coli JM109 when stx2A was overexpressed alone, while it was stably present when stxB was co-expressed. Compared with STx2 holotoxin, purified STx2A was degraded rapidly by periplasmic proteases when assessed for in vitro proteolytic susceptibility, suggesting that the B subunit contributes to stability of the toxin A subunit in the periplasm. We propose a novel role for toxin B subunits of AB5 toxins in protection of the A subunit from proteolysis during holotoxin assembly in the periplasm.

AB - Shiga toxin (STx) belongs to the AB5 toxin family and is transiently localized in the periplasm before secretion into the extracellular milieu. While producing outer membrane vesicles (OMVs) containing only A subunit of the toxin (STxA), we created specific STx1B- and STx2B-deficient mutants of E. coli O157:H7. Surprisingly, STxA subunit was absent in the OMVs and periplasm of the STxB-deficient mutants. In parallel, the A subunit of heat-labile toxin (LT) of enterotoxigenic E. coli (ETEC) was absent in the periplasm of the LT-B-deficient mutant, suggesting that instability of toxin A subunit in the absence of the B subunit is a common phenomenon in the AB5 bacterial toxins. Moreover, STx2A was barely detectable in the periplasm of E. coli JM109 when stx2A was overexpressed alone, while it was stably present when stxB was co-expressed. Compared with STx2 holotoxin, purified STx2A was degraded rapidly by periplasmic proteases when assessed for in vitro proteolytic susceptibility, suggesting that the B subunit contributes to stability of the toxin A subunit in the periplasm. We propose a novel role for toxin B subunits of AB5 toxins in protection of the A subunit from proteolysis during holotoxin assembly in the periplasm.

KW - Escherichia coli

KW - Heat-labile toxin

KW - Outer membrane

KW - Periplasm

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