Related Experiment Video
Updated: Feb 13, 2026
Optimized PCR-based Detection of Mycoplasma
Published on: June 20, 2011
Extracellular Actin Is a Receptor for Mycoplasma hyopneumoniae
Benjamin B A Raymond1, Ranya Madhkoor1, Ina Schleicher2
1The ithree Institute, Faculty of Science, University of Technology Sydney, Ultimo, NSW, Australia.
Abstract:
Mycoplasma hyopneumoniae, an agriculturally important porcine pathogen, disrupts the mucociliary escalator causing ciliostasis, loss of cilial function, and epithelial cell death within the porcine lung. Losses to swine production due to growth rate retardation and reduced feed conversion efficiency are severe, and antibiotics are used heavily to control mycoplasmal pneumonia. Notably, little is known about the repertoire of host receptors that M. hyopneumoniae targets to facilitate colonization. Here we show, for the first time, that actin exists extracellularly on porcine epithelial monolayers (PK-15) using surface biotinylation and 3D-Structured Illumination Microscopy (3D-SIM), and that M. hyopneumoniae binds to the extracellular β-actin exposed on the surface of these cells. Consistent with this hypothesis we show: (i) monoclonal antibodies that target β-actin significantly block the ability of M. hyopneumoniae to adhere and colonize PK-15 cells; (ii) microtiter plate binding assays show that M. hyopneumoniae cells bind to monomeric G-actin in a dose dependent manner; (iii) more than 100 M. hyopneumoniae proteins were recovered from affinity-chromatography experiments using immobilized actin as bait; and (iv) biotinylated monomeric actin binds directly to M. hyopneumoniae proteins in ligand blotting studies. Specifically, we show that the P97 cilium adhesin possesses at least two distinct actin-binding regions, and binds monomeric actin with nanomolar affinity. Taken together, these observations suggest that actin may be an important receptor for M. hyopneumoniae within the swine lung and will aid in the future development of intervention strategies against this devastating pathogen. Furthermore, our observations have wider implications for extracellular actin as an important bacterial receptor.
Insights
Mycoplasma hyopneumoniae, a swine pathogen, binds to extracellular actin on pig lung cells. This discovery reveals a new target for controlling pneumonia and improving swine production.
Area of Science:
- Veterinary Microbiology
- Cell Biology
- Host-Pathogen Interactions
Background:
- Mycoplasma hyopneumoniae causes significant losses in swine production by damaging lung tissue.
- Current treatments rely heavily on antibiotics, highlighting the need for alternative strategies.
- The specific host receptors targeted by M. hyopneumoniae for lung colonization remain largely unknown.
Purpose of the Study:
- To identify novel host receptors utilized by Mycoplasma hyopneumoniae for adherence and colonization of porcine lung epithelial cells.
- To investigate the role of extracellular actin as a potential receptor for M. hyopneumoniae.
Main Methods:
- Surface biotinylation and 3D-Structured Illumination Microscopy (3D-SIM) to detect extracellular actin.
- Monoclonal antibody blocking assays to assess the role of beta-actin in M. hyopneumoniae adhesion.
- Microtiter plate binding assays, affinity chromatography, and ligand blotting to characterize M. hyopneumoniae-actin interactions.
- Characterization of actin-binding regions within the M. hyopneumoniae P97 adhesin.
Main Results:
- Extracellular beta-actin was identified on porcine epithelial cells (PK-15).
- M. hyopneumoniae demonstrated dose-dependent binding to monomeric G-actin.
- Monoclonal antibodies targeting beta-actin significantly inhibited M. hyopneumoniae colonization.
- Over 100 M. hyopneumoniae proteins were found to interact with actin, with P97 adhesin showing high-affinity binding.
Conclusions:
- Extracellular actin serves as a significant receptor for M. hyopneumoniae attachment and colonization in swine lungs.
- The P97 adhesin plays a key role in mediating this interaction through specific actin-binding regions.
- Targeting extracellular actin presents a promising avenue for developing novel interventions against mycoplasmal pneumonia in pigs.
- Extracellular actin may represent a broadly important bacterial receptor.
Related Concept Videos
01:18Actin Treadmilling
01:21G-protein Coupled Receptors
01:26Introduction to Actin
01:42Actin Polymerization
The nucleation phase involves forming a stable nucleus consisting of three actin monomers to form a new actin filament. Actin-binding proteins such as formins and Arp2/3 complex help filament growth post-nucleation. The Formins form straight...
01:31Internal Receptors
01:42The Extracellular Matrix