Functional interactions between EB1 and the structural
MAP tau
Microtubules (MTs) are dynamic filaments that are
involved in important processes such as cell division and organelle transport.
These polymers are finely regulated by numerous MAPs (Microtubule Associated
Proteins). There are two major groups of MAPs: i) structural MAPs that bind
along the length wall of microtubules and stabilize them and ii) plus-end
tracking proteins (+TIPs) that specifically accumulate at the ends of growing
microtubules to control their dynamics and interactions with different cellular
structures. The +TIP EB1 (End binding 1) is considered as a master regulator of
microtubules, since it has the capacity to interact with several +TIPs and
other proteins via a consensus motif Ser-x-Ile-Pro (SxIP), and recruits them to
the microtubule extremity. In this work, we were interested to study the
potential interaction between EB1 and the structural MAP tau, which contains
one SxIP motif. Co-immunoprecipitation experiments in cellular extracts
revealed that EB1 and Tau interact. In addition, pull-down and yeast two-hybrid
assays confirmed that EB1 directly bind to tau. Finally, using purified
proteins we observed that tau reduces EB1 binding at MT ends by TIRF video-microscopy.
Together our results suggest an important role of tau as a direct regulator of
EB1 function.
