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Movements of Mycoplasma mobile Gliding Machinery Detected by High-Speed Atomic Force Microscopy
Kohei Kobayashi1, Noriyuki Kodera2, Taishi Kasai1
1Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka, Japan.
Abstract:
Mycoplasma mobile, a parasitic bacterium, glides on solid surfaces, such as animal cells and glass, by a special mechanism. This process is driven by the force generated through ATP hydrolysis on an internal structure. However, the spatial and temporal behaviors of the internal structures in living cells are unclear. In this study, we detected the movements of the internal structure by scanning cells immobilized on a glass substrate using high-speed atomic force microscopy (HS-AFM). By scanning the surface of a cell, we succeeded in visualizing particles, 2 nm in height and aligned mostly along the cell axis with a pitch of 31.5 nm, consistent with previously reported features based on electron microscopy. Movements of individual particles were then analyzed by HS-AFM. In the presence of sodium azide, the average speed of particle movements was reduced, suggesting that movement is linked to ATP hydrolysis. Partial inhibition of the reaction by sodium azide enabled us to analyze particle behavior in detail, showing that the particles move 9 nm right, relative to the gliding direction, and 2 nm into the cell interior in 330 ms and then return to their original position, based on ATP hydrolysis. IMPORTANCE The Mycoplasma genus contains bacteria generally parasitic to animals and plants. Some Mycoplasma species form a protrusion at a pole, bind to solid surfaces, and glide by a special mechanism linked to their infection and survival. The special machinery for gliding can be divided into surface and internal structures that have evolved from rotary motors represented by ATP synthases. This study succeeded in visualizing the real-time movements of the internal structure by scanning from the outside of the cell using an innovative high-speed atomic force microscope and then analyzing their behaviors.
Insights
Mycoplasma mobile uses internal structures powered by ATP hydrolysis for gliding motility. High-speed atomic force microscopy visualized these structures moving in real-time, revealing their precise motion linked to bacterial movement.
Area of Science:
- Microbiology
- Cell Biology
- Biophysics
Background:
- Mycoplasma mobile is a parasitic bacterium that glides on surfaces using a unique mechanism.
- This gliding motility is driven by force generated from ATP hydrolysis acting on internal structures.
- The precise spatial and temporal dynamics of these internal structures within living Mycoplasma cells remain largely uncharacterized.
Purpose of the Study:
- To visualize and analyze the real-time movements of internal structures involved in Mycoplasma mobile gliding.
- To elucidate the relationship between internal structure dynamics and ATP hydrolysis during gliding motility.
- To provide detailed insights into the mechanics of bacterial gliding at the nanoscale.
Main Methods:
- Utilized high-speed atomic force microscopy (HS-AFM) to scan immobilized Mycoplasma mobile cells.
- Visualized internal cellular particles, measuring approximately 2 nm in height and spaced 31.5 nm apart.
- Analyzed particle movement dynamics in the presence of sodium azide to assess the role of ATP hydrolysis.
Main Results:
- Successfully visualized internal particles aligned along the cell axis, consistent with prior electron microscopy findings.
- Observed that particle movement speed decreased significantly with sodium azide, indicating a link to ATP hydrolysis.
- Detailed analysis revealed that particles exhibit a specific motion: 9 nm lateral displacement and 2 nm inward movement within 330 ms, followed by a return to their original position, driven by ATP hydrolysis.
Conclusions:
- The study provides the first real-time visualization of internal structures driving Mycoplasma mobile gliding.
- The observed particle movements are directly correlated with ATP hydrolysis, confirming its role in generating motility force.
- These findings offer a deeper understanding of the rotary motor-like machinery evolved for bacterial gliding and infection.
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