Insights into EB1 structure and the role of its C-terminal domain for discriminating microtubule tips from the lattice

Abstract

EBs, key microtubule (MT) tip–tracking proteins, are elongated molecules with two interacting calponin homology (CH) domains, an arrangement reminiscent of MT- and actin-binding CH proteins. In addition, electrostatic interactions between the C-terminus of EBs and MTs drive the specificity of EBs for growing MT ends.

Interaction of mammalian end binding proteins with CAP-Gly domains of CLIP-170 and p150glued

“…This finding is in agreement with recent small angle X-ray scattering data suggesting that mammalian EBs adopt an elongated conformation in solution with no detectable interactions between the N-and C-terminal domains (Buey et al, 2011). The similar affinities measured for the EB3 homodimer and the EB13 heterodimer suggests that, at least with respect to CLIP-170 and p150 glued CAP-Gly binding, the two EB dimer versions are indistinguishable.…”

“…Full length human EB1, EB2, EB3 and EB1His were recombinantly produced and purified from bacteria as previously described (Buey et al, 2011;De Groot et al, 2010). The EB1-EB3 heterodimer (denoted EB13) was prepared by mixing equimolar amounts of EB1 and EB3 and incubation at room temperature for 2 days (De Groot et al, 2010).…”

Post-translational Modifications Regulate Assembly of Early Spindle Orientation Complex in Yeast

“…Together, these results suggest that the EB1 motif mediates dimerization of Bim1p(FL). Because full-length human EB1 is also dimeric (36), this seems to be a general feature of this protein class.…”

The microtubule end-binding protein EB2 is a central regulator of microtubule reorganisation in apico-basal epithelial differentiation

“…This suggests that EB1 may need to interact with formin in order to bind along the microtubule lattice or that formin-induced microtubule stabilisation facilitates EB1 lattice binding. Repulsive forces due to negative charges between the Cterminus of EB1 and the microtubule surface has been suggested to favour EB1 binding at the plus-end (Buey et al, 2011). It will be interesting in the future to determine whether formin binding to EB1 or microtubules reduces the repulsive forces and thus makes EB1 lattice association more favourable.…”

“…EBs form dimers and bind microtubules via their Nterminal calponin homology (CH) domain and recent evidence suggest that tip recognition is due to a high affinity for GTPtubulin, which is prominent at the growing end of microtubules (Dimitrov et al, 2008;Maurer et al, 2011;Maurer et al, 2012). Repulsive forces between the negatively charged C-terminus and the microtubule lattice are also likely to contribute to the plusend localisation (Buey et al, 2011). EB1 and EB3, but to a lesser extent EB2, interact via the C-terminus with most other +TIPs including APC (adenomatous polyposis coli), CLIPs (cytoplasmic linker proteins), CLASPs (CLIP-associated proteins) and the microtubule-actin cross-linking spectraplakin ACF7 (MACF1).…”