The structure of tubulin-binding cofactor A fromLeishmania majorinfers a mode of association during the early stages of microtubule assembly

Abstract

Tubulin-binding cofactor A (TBCA) participates in microtubule formation, a key process in eukaryotic biology to create the cytoskeleton. There is little information on how TBCA might interact with -tubulin en route to microtubule biogenesis. To address this, the protozoan Leishmania major was targeted as a model system. The crystal structure of TBCA and comparisons with three orthologous proteins are presented. The presence of conserved features infers that electrostatic interactions that are likely to involve the C-terminal tail of -tubulin are key to association. This study provides a reagent and template to support further work in this area.

Crystal structure of the C-terminal domain of tubulin-binding cofactor C from Leishmania major

“…This N-terminal domain carries a flexible and unstructured N-terminus, that interacts with tubulin, and this leads into a bundle of three α-helices [14] . The fold is similar to that of TBCA [11] . NMR structures of a truncated C-terminal fragment of human TBCC, consisting of 179 amino acids are deposited in the PDB (code 2yuh, unpublished).…”

“…The tubulin-binding cofactors (TBC) are then involved in heterodimer assembly and polymerization [4,5,8] . The proteins involved are highly conserved across species and we are exploiting trypanosomatids as the model system to help dissect the contributions that they make to microtubule assembly [9–11] .…”

Structure of the 34 kDa F-actin-bundling protein ABP34 fromDictyostelium discoideum

“…The top hit is tubulin-binding cofactor A (CoA) from Leishmania major (PDB entry 4cqi; Z-score of 8.9; r.m.s.d. of 3.6 Å over 87 C atoms; Barrack et al, 2015), followed by Hsp70, -spectrin, tubulin-specific chaperone A etc. ( Supplementary Table S3).…”