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Updated: Sep 30, 2025

Recombinant Protein Expression, Crystallization, and Biophysical Studies of a Bacillus-conserved Nucleotide Pyrophosphorylase, BcMazG
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Presence and function of Hbl B', the fourth protein component encoded by the hbl operon in Bacillus cereus

Nadja Jessberger1, Richard Diedrich2, Robert Janowski3

  • 1Institute for Food Quality and Food Safety, University of Veterinary Medicine Hannover, Hannover, Germany.

Virulence
|March 16, 2022
PubMed

Insights

The Hbl B

Area of Science:

  • Microbiology
  • Molecular Biology
  • Protein Biochemistry

Background:

  • Haemolysin BL (Hbl) is a pore-forming enterotoxin produced by Bacillus cereus.
  • The Hbl complex consists of three main components: Hbl L2, L1, and B.
  • The presence and function of an additional component, Hbl B', were previously unknown.

Purpose of the Study:

  • To investigate the expression and function of the Hbl B' protein in Bacillus cereus.
  • To develop a detection method for Hbl B' in bacterial culture supernatants.
  • To elucidate the role of Hbl B' in the Hbl toxin's activity.

Main Methods:

  • Analysis of hblB gene expression in Bacillus cereus strains.
  • Development of a detection system using a monoclonal antibody (11A5).
  • Assessment of cytotoxic and haemolytic activity with and without recombinant Hbl B' (rHbl B').

Main Results:

  • The hblB gene is expressed, and Hbl B' protein is secreted by most B. cereus strains.
  • A reliable detection system for Hbl B' was established.
  • rHbl B' significantly reduced Hbl's cytotoxic and haemolytic activity by interacting with Hbl L1.
  • Hbl B' acts as a regulator of Hbl complex formation.

Conclusions:

  • Hbl B' is a widely expressed and secreted component of the Hbl toxin in B. cereus.
  • Hbl B' plays a crucial regulatory role in Hbl toxin activity by controlling subunit complexation.
  • A novel tool for Hbl B' detection is now available, aiding further research into B. cereus pathogenicity.

Keywords:
Bacillus cereusHbl B’cytotoxicityenterotoxinhaemolysin BLhblBpore formationpore forming toxintripartite

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