Direct interaction between prion protein and tubulin

Recently published data show that the prion protein in its cellular form (PrPC) is a component of multimolecular complexes. In this report, zero-length cross-linking with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) allowed us to identify tubulin as one of the molecules interacting with PrPC in complexes observed in porcine brain extracts. We found that porcine brain tubulin added to these extracts can be cross-linked with PrPC. Moreover, we observed that the 34 kDa species identified previously as full-length diglycosylated prion protein co-purifies with tubulin. Cross-linking of PrPC species separated by Cu2+-loaded immobilized metal affinity chromatography confirmed that only the full-length protein but not the N-terminally truncated form (C1) binds to tubulin. By means of EDC cross-linking and cosedimentation experiments, we also demonstrated a direct interaction of recombinant human PrP (rPrP) with tubulin. The stoichiometry of cosedimentation implies that rPrP molecules are able to bind both the α- and β-isoforms of tubulin composing microtubule. Furthermore, prion protein exhibits higher affinity for microtubules than for unpolymerized tubulin.