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Updated: Feb 5, 2026
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Improvement of Bacillus subtilis Spore Enumeration and Label Analysis in Flow Cytometry
Published on: June 30, 2023
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Bacillus subtilis aconitase is an RNA-binding protein
1Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA.
Summary
Bacillus subtilis aconitase binds iron response elements (IREs) in RNA, similar to eukaryotes. This RNA binding, not enzymatic activity, enhances bacterial sporulation under iron deficiency.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Aconitase is a key enzyme in the Krebs cycle.
- In eukaryotes, aconitase-like proteins regulate iron metabolism via iron-responsive elements (IREs) in mRNA.
- The function of bacterial aconitase in RNA binding and iron regulation is less understood.
Purpose of the Study:
- To investigate the RNA binding capabilities of Bacillus subtilis aconitase.
- To determine if bacterial aconitase interacts with iron-responsive elements (IREs).
- To explore the role of aconitase's non-enzymatic functions in bacterial physiology, particularly sporulation.
Main Methods:
- In vitro RNA binding assays using B. subtilis aconitase and IRE sequences.
- Analysis of IRE binding activity under varying iron concentrations (in vivo and in vitro).
- Comparison of sporulation efficiency between wild-type, aconitase null mutant, and enzymatically inactive aconitase mutant strains of B. subtilis.
Main Results:
- Bacillus subtilis aconitase specifically binds to sequences similar to eukaryotic IREs, including rabbit ferritin IRE and IRE-like sequences in B. subtilis.
- IRE binding activity is modulated by iron availability.
- An enzymatically inactive aconitase mutant retained RNA binding ability and exhibited significantly enhanced sporulation (40x) compared to an aconitase null mutant.
Conclusions:
- Bacterial aconitases, like eukaryotic homologs, are bifunctional proteins.
- Aconitase possesses RNA binding activity, particularly important under iron-deprived conditions.
- Non-enzymatic RNA binding by aconitase plays a crucial role in B. subtilis sporulation, independent of its catalytic function.
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