How can a surface guide centriole assembly?

Centrioles are cell organelles with a cylindrical shape and a 9-fold radially symmetric architecture. They play a role in the formation of cilia and flagella and originate the mitotic spindle during cell division. Further, as a major component in centrosomes, they are involved in microtubule organization.

At the center of each centriole is the cartwheel, which consists of SAS-6 proteins that self-assemble into stacked ring polymers on the surface of a torus surrounding the mother centriole to initiate growth of a new centriole. So far it was unclear how the intrinsically helical SAS-6 polymers assemble into flat rings and how the symmetry is determined.

Researchers from the MBM-group teamed up with Pierre Gönczys lab in Lausanne. Their investigation on the assembly dynamics of SAS-6 using photothermally-actuated, off-resonance tapping high-speed atomic force microscopy showed that the affinity of SAS-6 head domains is increased by four orders of magnitude on a surface compared to in solution. Coarse-grained molecular dynamics simulations additionally revealed that the presence of a surface favors angles between the SAS-6 monomers compatible with the signature 9-fold symmetry. Remnants of the proteins helical features are reflected in its C-terminal tail domain orientations, which likely aids ring stacking.

Check out the combined results that have recently been published in Nature Communications:

Niccolò Banterle, Adrian P. Nievergelt, Svenja de Buhr, Georgios N. Hatzopoulos, Charlène Brillard, Santiago Andany, Tania Hübscher, Frieda A. Sorgenfrei, Ulrich S. Schwarz, Frauke Gräter, Georg E. Fantner & Pierre Gönczy. Kinetic and structural roles for the surface in guiding SAS-6 self-assembly to direct centriole architecture. Nature Communications 12, (2021)