The structured core of human ? tubulin confers isotype-specific polymerization properties.

ABSTRACT: Diversity in cytoskeleton organization and function may be achieved through variations in primary sequence of tubulin isotypes. Recently, isotype functional diversity has been linked to a "tubulin code" in which the C-terminal tail, a region of substantial sequence divergence between isotypes, specifies interactions with microtubule-associated proteins. However, it is not known whether residue changes in this region alter microtubule dynamic instability. Here, we examine recombinant tubulin with human ? isotype IIB and characterize polymerization dynamics. Microtubules with ?IIB have catastrophe frequencies approximately threefold lower than those with isotype ?III, a suppression similar to that achieved by regulatory proteins. Further, we generate chimeric ? tubulins with native tail sequences swapped between isotypes. These chimeras have catastrophe frequencies similar to that of the corresponding full-length construct with the same core sequence. Together, our data indicate that residue changes within the conserved ? tubulin core are largely responsible for the observed isotype-specific changes in dynamic instability parameters and tune tubulin's polymerization properties across a wide range.

SUBMITTER: Pamula MC 

PROVIDER: S-EPMC4878094 | biostudies-literature | 2016 May

REPOSITORIES: biostudies-literature