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Cyclic Di-AMP Affects Cell Membrane Integrity of Streptococcus pneumoniae

Tiffany M Zarrella1, Jianle Gao1, Nathan Forrest1

  • 1Department of Immunology and Microbial Disease, Albany Medical College, Albany, New York, USA.

Molecular Microbiology
|June 27, 2025
PubMed

Insights

Cyclic di-adenosine monophosphate (c-di-AMP) impacts Streptococcus pneumoniae cell membrane integrity. Lowering c-di-AMP levels in cdaA* mutants rescues growth defects caused by competence-stimulating peptide (CSP).

Area of Science:

  • Microbiology
  • Molecular Biology
  • Biochemistry

Background:

  • The bacterial second messenger cyclic di-adenosine monophosphate (c-di-AMP) is known to modulate competence in Streptococcus pneumoniae.
  • A cdaA* mutant, with reduced c-di-AMP levels, unexpectedly shows susceptibility to competence-stimulating peptide (CSP).

Purpose of the Study:

  • To investigate the mechanism behind the CSP susceptibility in the cdaA* Streptococcus pneumoniae strain.
  • To identify genetic factors that suppress the CSP susceptibility and explore the role of c-di-AMP in cell membrane integrity.

Main Methods:

  • Screening of cdaA* suppressor mutants resistant to CSP.
  • Sequencing of mutated clones to identify genetic alterations.
  • Analysis of gene deletions and promoter modifications related to FabT and K+ uptake.
  • Assessment of c-di-AMP phosphodiesterase-null mutants' sensitivity to ethanol and Triton X-100.

Main Results:

  • Mutations in the c-di-AMP phosphodiesterase Pde1 and the transcription factor FabT were identified in CSP-resistant suppressor mutants.
  • Deletion of fabT, disruption of its binding site, deletion of briC, or disruption of K+ uptake rescued the growth defect of the cdaA* mutant in CSP media.
  • A c-di-AMP phosphodiesterase-null mutant exhibited high sensitivity to ethanol and Triton X-100, which was ameliorated by reducing c-di-AMP levels.

Conclusions:

  • c-di-AMP levels are correlated with CSP susceptibility in Streptococcus pneumoniae.
  • c-di-AMP plays a significant role in maintaining cell membrane integrity, affecting sensitivity to membrane-damaging agents.
  • The findings reveal a novel link between c-di-AMP signaling, cell membrane homeostasis, and bacterial competence.
Keywords:
Streptococcus pneumoniaeCdaAcompetencec‐di‐AMPdiadenylate cyclasemembrane integritypotassium transport

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