Download MendeleyCoiled-coil-mediated phase separation of Spef1 for central-pair microtubule organization and function.
Ren, J., Liu, J., Gu, K., Li, D., Qiu, B., Zhu, X., Feng, W.(2026) Structure 34: 718-731.e6
- PubMed: 41812652 Search on PubMed
- DOI: https://doi.org/10.1016/j.str.2026.02.007
- Primary Citation Related Structures:
9IJX - PubMed Abstract:
Central-pair microtubules (CP-MTs) are non-centrosomal MTs essential for planar beat pattern of cilia. The CP-MT formation requires the MT-associated protein Spef1, but the underlying molecular mechanism remains unclear. Here, we show that Spef1 undergoes liquid-liquid phase separation (LLPS) to facilitate non-centrosomal MT assembly by enriching tubulins. The LLPS of Spef1 is mediated by its C-terminal coiled-coil (CC) domain. Crystallography reveals that the Spef1-CC domain forms a parallel CC dimer with a unique charge distribution pattern on the surface. The dimerization capacity and charge distribution of Spef1-CC are both critical for controlling in vitro LLPS. Disruption of the dimerization capacity abolishes ciliary functions of Spef1. In contrast, a charge-changing mutant with attenuated LLPS still supports the CP-MT formation but results in cilia with abnormal beat pattern. Thus, the CC-mediated LLPS of Spef1 provides a mechanistic explanation for its prominent role in controlling CP-MT organization and function in the axoneme.
- State Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China. Electronic address: jinqi@ibp.ac.cn.
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