Gliding Motility Mechanisms in Mycoplasma Species

Mycoplasmas are wall-less bacteria that exhibit a distinctive form of surface translocation known as gliding motility. Unlike flagellar or pilus-driven locomotion, gliding in species such as Mycoplasma pneumoniae and Mycoplasma mobile relies on a specialized polar organelle. This structure comprises an external adhesin complex that binds sialylated oligosaccharides on host surfaces and an internal machinery that generates force through ATP hydrolysis. Key surface proteins, including P1 and P40/P90 in M. pneumoniae, form a nap-like array which alternately attaches to and releases from the substrate. Beneath this array, paired plates, a terminal button and a bowl-shaped complex are arranged to transmit conformational changes. In M. mobile, homologues of F₁-ATPase subunits assemble into “tentacle”-like or “chain”-like motors that convert chemical energy into mechanical motion. Repeated cycles of binding, pulling and detachment drive smooth, directional gliding at rates up to several micrometres per second. This motility facilitates colonisation of epithelial surfaces, contributes to immune evasion and has become a model for minimal-cell movement, with implications for antimicrobial strategies and synthetic biology.

Research from Nature Portfolio

Recent structural studies have elucidated the architecture of the transmembrane adhesion complex in M. pneumoniae. High-resolution X-ray crystallography and cryo-electron microscopy have revealed that the major adhesin P1 forms a heteromeric assembly with P40/P90, locating the sialic-acid binding site on P40/P90 rather than on P1 itself. Surface variability in the N-terminal domains of these proteins appears to underlie antigenic diversity, while conserved C-terminal regions present promising targets for inhibitory antibodies and vaccine design. In parallel, novel insights into lipid acquisition have emerged from single-particle cryo-EM of a homodimeric protein, revealing a large hydrophobic cavity specialised for extracting cholesterol and phospholipids from host membranes. Although primarily implicated in nutrient uptake, this lipid-binding protein may influence membrane fluidity and thereby modulate the mechanics of the gliding organelle.

Gliding Motility Mechanisms in Mycoplasma Species publication trend

The graph below shows the total number of articles in gliding motility mechanisms in mycoplasma species across all publications each year (not limited to Nature Index journals).

Technical terms

Gliding motility: A form of bacterial locomotion on surfaces that does not involve flagella or pili, driven by specialised protein machineries.

Attachment organelle: A polar cellular protrusion in gliding mycoplasmas that houses both the surface adhesin complex and the internal motor apparatus.

Sialylated oligosaccharides: Carbohydrate receptors bearing sialic acid residues on host cell surfaces, recognised by mycoplasmal adhesins.

F₁-ATPase: A rotary enzyme complex that normally synthesises ATP; homologous subunits form the motor core in some mycoplasmal gliding systems.

Cryo-electron microscopy: A structural biology technique in which samples are studied at cryogenic temperatures to reveal high-resolution three-dimensional assemblies.

Adhesin complex: A multimeric assembly of proteins on the bacterial surface that mediates attachment to substrates during gliding.

References

1. Essential protein P116 extracts cholesterol and other indispensable lipids for Mycoplasmas. Nature Structural & Molecular Biology (2023).
2. Immunodominant proteins P1 and P40/P90 from human pathogen Mycoplasma pneumoniae. Nature Communications (2020).
3. Integrated Information and Prospects for Gliding Mechanism of the Pathogenic Bacterium Mycoplasma pneumoniae. Frontiers in Microbiology (2016).
4. Systematic Structural Analyses of Attachment Organelle in Mycoplasma pneumoniae. PLOS Pathogens (2015).
5. Refined Mechanism of Mycoplasma mobile Gliding Based on Structure, ATPase Activity, and Sialic Acid Binding of Machinery. mBio (2019).
6. Chained Structure of Dimeric F1-like ATPase in Mycoplasma mobile Gliding Machinery. mBio (2021).