Kinesin-like calmodulin-binding protein (KCBP) is a unique kinesin with half kinesin and half myosin, with kinesin motor domain at C-terminus and myosin tail homology region 4 (MyTH4) and band 4.1, ezrin, radixin, moesin (FERM) domains at N-terminus. The special structure endows KCBP multi-intracellular functions, including cell division, trichome morphogenesis in plants, and flagellar function in algae. However, little is known about the molecular mechanism underlying these functions. Here, we identified a molecular chaperone Hsp90 as a novel binding partner with KCBP in Dunaliella salina using a yeast two-hybrid screen. Further analysis showed that Hsp90 interacted with both the N-terminal and C-terminal of DsKCBP. Since Hsp90 was involved in the stability and proteolytic turnover of numerous proteins, whether Hsp90 regulated the degradation of DsKCBP was investigated. Our results showed that both Hsp90 and DsKCBP presented in the purified proteasome, and the interaction of DsKCBP-Hsp90 was inhibited upon Hsp90 inhibitor geldanamycin treatment. The level of DsKCBP proteins was diminished remarkably indicating that the disassociation of DsKCBP from Hsp90 accelerated the degradation of the former. Furthermore, immunofluorescence results showed that the localization of DsKCBP at basal body and flagella was disappeared by Hsp90 inhibition. The increased mRNA level of DsKCBP during flagellar assembly was not obvious by geldanamycin treatment. These data provided evidence that Hsp90 protected DsKCBP from degradation by proteasome and was involved in the role of DsKCBP in flagellar assembly.

驱动蛋白样钙调蛋白结合蛋白 (KCBP) 是一种独特的驱动蛋白，具有一半驱动蛋白和一半肌球蛋白，在 C 端具有驱动蛋白运动结构域和肌球蛋白尾部同源区 4 (MyTH4) 和带 4.1、ezrin、radixin、moesin (FERM) N端的结构域。这种特殊的结构赋予了 KCBP 多种细胞内功能，包括细胞分裂、植物中的毛状体形态发生和藻类中的鞭毛功能。然而，关于这些功能背后的分子机制知之甚少。在这里，我们在杜氏盐藻中鉴定出一种分子伴侣 Hsp90 作为与 KCBP 的新型结合伙伴。使用酵母双杂交筛选。进一步分析表明，Hsp90 与 DsKCBP 的 N 端和 C 端相互作用。由于 Hsp90 参与多种蛋白质的稳定性和蛋白水解转换，因此研究了 Hsp90 是否调节 DsKCBP 的降解。我们的结果表明，Hsp90 和 DsKCBP 都存在于纯化的蛋白酶体中，并且在 Hsp90 抑制剂格尔德霉素处理后，DsKCBP-Hsp90 的相互作用受到抑制。DsKCBP 蛋白水平显着降低，表明 DsKCBP 与 Hsp90 的分离加速了前者的降解。此外，免疫荧光结果显示，DsKCBP在基体和鞭毛的定位因Hsp90的抑制而消失。在鞭毛组装过程中 DsKCBP mRNA 水平的增加在格尔德霉素处理下并不明显。这些数据提供了证据表明 Hsp90 保护 DsKCBP 免受蛋白酶体降解，并参与 DsKCBP 在鞭毛装配中的作用。