News from CRG
Microtubules are the skeleton of individual cells, providing eukaryotic cells with their structure and shape. Made up of different types of the protein tubulin, microtubules also act as a network of self-assembling highways to transport large molecular materials from one side of a cell to another.
The process that kickstarts microtubule nucleation, by which new microtubules are formed, has been an area of intensive research. It has been known for decades that microtubules are nucleated by the g-tubulin ring complex (gTuRC), but the mechanisms by which it works are unknown.
Now research started by Thomas Surrey’s lab at the Francis Crick Institute in London and finished at the Centre for Genomic Regulation (CRG), uncovers how gTuRC acts as a scaffold to make new microtubules. Working jointly with Alessandro Costa at the Francis Crick and Juri Rappsilber at the Wellcome Trust Centre in Edinburgh and Technical University in Berlin, the team finds that purified gTuRC nucleates microtubules surprisingly inefficiently, although it caps one end of a microtubule well, once nucleation has taken place.
The researchers believe that this is a consequence of the peculiar structure of gTuRC, which deviates slightly on one side deterring it from attaining the perfect conical shape that would otherwise make it fit well to the microtubule geometry. The findings suggest that a conformational change induced by proteins that regulate gTuRC, or by posttranslational modifications, is required to activate the process to make new microtubules, providing new insight into the molecular mechanism regulating microtubule nucleation in cells.