Atomic power microscopy reveals microtubule defects at submolecular decision

In a research just lately revealed within the journal Nano Letters, researchers from Nano Life Science Institute (WPI-NanoLSI), Kanazawa College, Kanazawa, Japan, used frequency-modulated atomic power microscopy to disclose the submolecular construction of microtubule (MT) inside floor and visualize structural defects within the MT lattice, offering useful insights into the complicated dynamic processes that regulate microtubule operate.

Microtubules (MTs), a key part of the cytoskeleton in eukaryotic cells, function scaffolds and play very important roles in mobile processes akin to cell division, cell migration, intracellular transport, and trafficking. MTs are composed of α-tubulin and β-tubulin proteins, which polymerize into dimers and assemble into linear protofilaments that type a cylindrical lattice.

Conventional strategies like X-ray crystallography and cryo-electron microscopy have supplied structural insights into MTs however contain complicated pattern preparation and knowledge evaluation. There stays a necessity for methods that may look at MT structural options, meeting dynamics, and lattice defects at submolecular decision below physiological situations.

The outer floor of the MT wall has been extensively studied. Nonetheless, restricted research have examined the submolecular association of tubulin dimers within the inside MT wall. The outer and inside partitions of MTs work together with totally different proteins.

To deal with this hole, a staff of scientists led by Ayhan Yurtsever, Hitoshi Asakawa, and Takeshi Fukuma at Nano Life Science Institute (WPI-NanoLSI), Kanazawa College, employed frequency-modulation atomic power microscopy (FM-AFM) to check the submolecular association of tubulin dimers on each the inside and outer MT surfaces (see fig. 1). The inside MT floor exhibited a corrugated construction, whereas the outer floor exhibited shallow undulations (see fig. 2).

One protofilament was topographically greater than its adjoining protofilament. This differential topography was attributable to variations within the structural orientations and conformation of αβ-tubulin heterodimers between adjoining protofilaments. The α-tubulin and β-tubulin monomers of the protofilaments on the inside floor reoriented in the course of the structural transition from tubes to sheets.

The inside floor additionally had a “seam” line, which is taken into account to confer flexibility to MTs. FM-AFM enabled the detection of a number of lattice or structural defects attributable to lacking tubulin subunits alongside the protofilaments within the MT lattice shaft within the localized area. These defects can alter the molecular association of protofilaments and consequently impair the features of MTs.

The research additionally explored MT interactions with Taxol, a chemotherapy drug that solely binds to β-tubulin subunits inside αβ-tubulin dimers on the inside MT floor. Taxol-stabilized microtubules inhibit most cancers cell division and migration, thereby probably slowing most cancers development.

This binding served as a marker to differentiate particular person α- and β-tubulin subunits in high-resolution AFM photographs. This perception underscores FM-AFM’s potential to research the molecular mechanisms of medication that concentrate on MTs.

In abstract, FM-AFM supplies vital insights into MT construction, dynamics, and drug interactions, revealing the potential for advancing drug discovery. Understanding MT operate and protein interactions can information the event of extra particular and environment friendly therapies, significantly for most cancers, the place MTs are key therapeutic targets.