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The Microbial Anti-Inflammatory Molecule (MAM) is a key protein processed and exported to Faecalibacterium duncaniae

Thaís Vilela Rodrigues1,2, Sylvain Marthey3, Sandrine Auger1

  • 1Université Paris Saclay, INRAE, AgroParisTech, MICALIS, Jouy-enJosas, France.

Gut Microbes
|June 18, 2025
PubMed

Insights

Microbial-Anti-Inflammatory Molecule (MAM) from Faecalibacterium duncaniae is localized to the bacterial surface and forms hexamers. This reveals its role in the gut bacterium

Area of Science:

  • Microbiology
  • Structural Biology
  • Bioinformatics

Background:

  • Faecalibacterium duncaniae is a key human gut microbe.
  • Microbial-Anti-Inflammatory Molecule (MAM) is crucial for F. duncaniae's anti-inflammatory properties.
  • MAM's structure and function are poorly understood.

Purpose of the Study:

  • To investigate the cellular localization, secretion, and structural organization of MAM.
  • To understand the molecular mechanisms behind MAM's transport and assembly.
  • To explore the role of MAM in the F. duncaniae cell envelope.

Main Methods:

  • Mass spectrometry and immunogold labeling for protein localization.
  • Bioinformatic and in silico analyses for predicting transport mechanisms.
  • AlphaFold3 modeling and docking for structural prediction.
  • Electron microscopy for visualizing surface organization.

Main Results:

  • MAM is the most abundant protein in the F. duncaniae cell envelope and the second most abundant overall.
  • MAM is localized to the bacterial surface.
  • A novel transport pathway involving a Peptidase-domain-Containing ABC Transporter (PCAT) is proposed for MAM.
  • MAM assembles into hexamers with a lattice-like organization on the bacterial surface.

Conclusions:

  • MAM is a key component of the F. duncaniae cell envelope, playing a significant role in its unique biology.
  • The findings provide insights into the structure and function of MAM.
  • This study supports the potential of F. duncaniae as a next-generation probiotic or live biotherapeutic.
Keywords:
ABC transporterCell envelopeFaecalibacteriuminflammationleader and cargo peptidesmicrobiotaproteomics

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