Control of actin moving trajectory by patterned poly(methylmethacrylate) tracks

Area of Science:

• Biophysics
• Materials Science
• Cell Biology

Background:

• Heavy meromyosin (HMM) is crucial for actin filament movement.
• Immobilizing HMM on specific substrates is essential for studying motility.
• Poly(methylmethacrylate) (PMMA) is a photoresist polymer with potential for biomolecule immobilization.

Purpose of the Study:

• To evaluate PMMA as a substrate for immobilizing HMM molecules.
• To investigate the precise movement of actin filaments on patterned PMMA tracks.
• To compare actin motility on PMMA with conventional substrates.

Main Methods:

• Fabrication of PMMA tracks (lines, circles, letters) using UV photolithography.
• Immobilization of HMM molecules onto PMMA tracks via adsorption.
• In vitro motility assay observing rhodamine-phalloidin labeled actin filaments using epifluorescence microscopy.
• Atomic Force Microscopy (AFM) to characterize PMMA track dimensions.

Main Results:

• Actin filaments moved precisely along the fabricated PMMA tracks, mirroring their shapes.
• PMMA successfully immobilized HMM, retaining its motor function.
• The mean velocity of actin movement on PMMA was 4.5 mm/s at 25°C.
• AFM confirmed track dimensions (1-2 microns wide, ~200 nm high).

Conclusions:

• PMMA is a suitable material for creating patterned substrates for HMM-based in vitro motility assays.
• This technique allows for precise control and observation of actin filament movement along defined paths.
• PMMA offers a viable alternative to traditional nitrocellulose films for actin motility studies.