MATCAP1 preferentially binds an expanded tubulin conformation to generate detyrosinated and ΔC2 α-tubulin

Microtubules are cytoskeletal filaments with critical roles in cell division, cell motility, intracellular trafficking, and cilium function. In cells, subsets of microtubules are selectively marked by posttranslational modifications (PTMs) that control the ability of microtubule-associated proteins (MAPs) and molecular motors to engage microtubules. Detyrosination (ΔY) and ΔC2 are PTMs of α-tubulin wherein one or two residues, respectively, are enzymatically removed from the C-terminus of the protein. How specific patterns of PTMs are generated in cells is incompletely understood. Here, we use in vitro reconstitution assays to investigate the microtubule-binding behavior of metallopeptidase MATCAP1 and the mechanism by which it generates ΔY and ΔC2 modifications of α-tubulin. We demonstrate that MATCAP1 preferentially binds to microtubules composed of tubulin subunits in an expanded conformation, which can be induced by preventing β-tubulin GTP hydrolysis, taxol treatment, or kinesin-1 stepping. MATCAP1 exhibits a long dwell-time on microtubules and sequentially removes residues to generate ΔY-microtubules and ΔC2-microtubules. Thus, the lattice conformation of microtubules is a key factor that gates the binding and activity of MATCAP1.