Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, USA.
J Cell Biol. 2024 Aug 5;223(8). doi: 10.1083/jcb.202311104. Epub 2024 May 14.
Basal bodies (BBs) are conserved eukaryotic structures that organize cilia. They are comprised of nine, cylindrically arranged, triplet microtubules (TMTs) connected to each other by inter-TMT linkages which stabilize the structure. Poc1 is a conserved protein important for BB structural integrity in the face of ciliary forces transmitted to BBs. To understand how Poc1 confers BB stability, we identified the precise position of Poc1 in the Tetrahymena BB and the effect of Poc1 loss on BB structure. Poc1 binds at the TMT inner junctions, stabilizing TMTs directly. From this location, Poc1 also stabilizes inter-TMT linkages throughout the BB, including the cartwheel pinhead and the inner scaffold. The full localization of the inner scaffold protein Fam161A requires Poc1. As ciliary forces are increased, Fam161A is reduced, indicative of a force-dependent molecular remodeling of the inner scaffold. Thus, while not essential for BB assembly, Poc1 promotes BB interconnections that establish an architecture competent to resist ciliary forces.
基体（BBs）是保守的真核结构，它们组织纤毛。它们由九个圆柱形排列的三联微管（TMTs）组成，通过 TMT 之间的连接相互连接，这些连接稳定了结构。Poc1 是一种保守的蛋白质，对于面对传递到 BB 的纤毛力时保持 BB 结构完整性很重要。为了了解 Poc1 如何赋予 BB 稳定性，我们确定了 Tetrahymena BB 中 Poc1 的精确位置以及 Poc1 缺失对 BB 结构的影响。Poc1 结合在 TMT 内连接点上，直接稳定 TMT。从这个位置，Poc1 还稳定了整个 BB 中的 TMT 之间的连接，包括车轮辐条钉头和内支架。内支架蛋白 Fam161A 的完全定位需要 Poc1。随着纤毛力的增加，Fam161A 减少，表明内支架发生了依赖于力的分子重塑。因此，虽然 Poc1 对于 BB 组装不是必需的，但它促进了 BB 之间的连接，从而建立了一种能够抵抗纤毛力的结构。
