An evolution-conserved allosteric network in human tubulin governs paclitaxel efficacy

Area of Science:

• Biochemistry
• Molecular Biology
• Structural Biology

Background:

• Paclitaxel is a vital anti-cancer drug targeting microtubules.
• The molecular mechanisms linking tubulin variants to paclitaxel efficacy are not fully understood.

Purpose of the Study:

• To elucidate how tubulin isotypes and mutations influence paclitaxel drug efficacy.
• To identify conserved tubulin residues that modulate the allosteric network affecting paclitaxel response.

Main Methods:

• Cryo-electron microscopy (cryo-EM) at ~2.3 Å resolution to reconstruct microtubules.
• Analysis of genome-edited cancer cells expressing paclitaxel-sensitized tubulin mutants.
• Investigation of allosteric networks, intertubulin interactions, and nucleotide-binding pockets.

Main Results:

• Paclitaxel resistance in human β3-tubulin is linked to a residue distant from the binding site.
• A paclitaxel-sensitizing mutation induces allosteric changes impacting drug binding, microtubule dynamics, and nucleotide pockets.
• The α-tubulin E254 residue reorientation enhances the GTP cap, decreasing microtubule catastrophe frequency.
• Tubulin variant affinity for paclitaxel directly correlates with drug efficacy in cancer cells.

Conclusions:

• Conserved tubulin residues are critical for modulating paclitaxel efficacy through allosteric networks.
• Understanding tubulin variant-specific drug interactions is key for developing next-generation tubulin-targeting therapeutics.
• These findings offer insights for both cancer treatment and managing tubulinopathies.