Oral Actinobacteria sense and defend against parasitic epibionts

Abstract

Bacteria contend with a wide range of antagonistic interactions from neighboring microbes. One widespread but poorly understood threat is posed by Patescibacteria, which proliferate by colonizing host bacteria surfaces and extracting cellular resources. Despite the ubiquity of Patescibacteria in the environment, how hosts defend against these epibionts remains unknown. Here we show that Actinomycetota fend off Patescibacteria using the Esx secretion system. We identify a secreted effector protein that mediates this defensive behavior and demonstrate that Esx induction is part of a multifaceted, epibiont-specific response that includes multiple predicted cell surface modifications. Finally, we show that this response occurs at the transcriptional level and is mediated by a previously undescribed threat sensing pathway whose activation leads to threonine phosphorylation of an FHA domain-containing output protein. Together with bioinformatic evidence linking this threat sensing pathway to Esx across Actinomycetales, our experimental findings establish a functional role for the elusive and broadly distributed Esx pathway in defense against epibionts. Furthermore, they help resolve the ecological relationship between Patescibacteria and their hosts as one of antagonism, not mutualism.

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Cite

BibTeX RIS

BibTeX

@misc{wang2026oral,
  title = {{Oral Actinobacteria sense and defend against parasitic epibionts}},
  author = {Y. Wang and J. Colautti and L. A. Gallagher and J. Lee and Y. Tan and S. Farrell and C. Farrell and B. Bor and J. C. Whitney and D. Zhang and S. B. Peterson and J. D. Mougous},
  howpublished = {bioRxiv},
  year = {2026},
  month = sep,
  doi = {10.64898/2026.09.08.750141},
  url = {https://www.biorxiv.org/content/10.64898/2026.09.08.750141v1},
  note = {CC BY},
}

RIS

TY  - UNPB
TI  - Oral Actinobacteria sense and defend against parasitic epibionts
AU  - Y. Wang
AU  - J. Colautti
AU  - L. A. Gallagher
AU  - J. Lee
AU  - Y. Tan
AU  - S. Farrell
AU  - C. Farrell
AU  - B. Bor
AU  - J. C. Whitney
AU  - D. Zhang
AU  - S. B. Peterson
AU  - J. D. Mougous
PY  - 2026
DA  - 2026/09/08
PB  - bioRxiv
DO  - 10.64898/2026.09.08.750141
UR  - https://www.biorxiv.org/content/10.64898/2026.09.08.750141v1
AB  - Bacteria contend with a wide range of antagonistic interactions from neighboring microbes. One widespread but poorly understood threat is posed by Patescibacteria, which proliferate by colonizing host bacteria surfaces and extracting cellular resources. Despite the ubiquity of Patescibacteria in the environment, how hosts defend against these epibionts remains unknown. Here we show that Actinomycetota fend off Patescibacteria using the Esx secretion system. We identify a secreted effector protein that mediates this defensive behavior and demonstrate that Esx induction is part of a multifaceted, epibiont-specific response that includes multiple predicted cell surface modifications. Finally, we show that this response occurs at the transcriptional level and is mediated by a previously undescribed threat sensing pathway whose activation leads to threonine phosphorylation of an FHA domain-containing output protein. Together with bioinformatic evidence linking this threat sensing pathway to Esx across Actinomycetales, our experimental findings establish a functional role for the elusive and broadly distributed Esx pathway in defense against epibionts. Furthermore, they help resolve the ecological relationship between Patescibacteria and their hosts as one of antagonism, not mutualism.
ER  -

Abstract

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