Tubulin Zone Occupancy by PDB-Deposited Colchicine Binding Site Inhibitors.

Area of Science:

• Biochemistry and Molecular Biology
• Pharmacology
• Agricultural Science

Background:

• Microtubules, formed by tubulin polymerization, are vital for cell function and are key targets for cancer, inflammation, and parasitic disease treatments.
• Microtubules also have agricultural applications as herbicides and fungicides.
• The colchicine binding site (COLbs) is a well-studied target, accommodating diverse ligands across three zones (Z1-Z3).

Purpose of the Study:

• To analyze existing colchicine-site inhibitors and their interaction profiles.
• To classify these inhibitors based on a three-zone model of the colchicine binding site.
• To identify emerging mechanisms of action for COLbs ligands, such as tubulin degradation.

Main Methods:

• Analysis of over 160 colchicine-site inhibitors from the Protein Data Bank.
• Application of a three-zone classification model (Z1-Z3) to categorize inhibitors by molecular similarity and interaction patterns.
• Examination of ligand binding within the central Z2 region and extensions into Z1 and Z3.

Main Results:

• Inhibitors were grouped based on their binding similarities and interaction profiles within the Z1-Z3 zones.
• The study identified diverse binding modes and interaction characteristics across the different zones.
• Emerging mechanisms, including tubulin degradation, were highlighted as potential modes of action for COLbs ligands.

Conclusions:

• The three-zone model provides a framework for understanding COLbs ligand diversity and interactions.
• Emerging mechanisms like tubulin degradation offer new avenues for therapeutic and agricultural applications.
• This analysis informs the rational design of next-generation tubulin polymerization inhibitors.