Ren Jinqi, Li Dong, Liu Juyuan, Liu Hao, Yan Xiumin, Zhu Xueliang, Feng Wei
National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China.
National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China.
Cell Rep. 2022 Nov 8;41(6):111589. doi: 10.1016/j.celrep.2022.111589.
Calmodulin-regulated spectrin-associated proteins (Camsaps) bind to the N-terminal domain of WD40-repeat 47 (Wdr47-NTD; featured with a LisH-CTLH motif) to properly generate axonemal central-pair microtubules (CP-MTs) for the planar beat pattern of mammalian motile multicilia. The underlying molecular mechanism, however, remains unclear. Here, we determine the structures of apo-Wdr47-NTD and Wdr47-NTD in complex with a characteristic Wdr47-binding region (WBR) from Camsap3. Wdr47-NTD forms an intertwined dimer with a special cross-over region (COR) in addition to the canonical LisH and globular α-helical core (GAC). The basic WBR peptide adopts an α-helical conformation and anchors to a tailored acidic pocket embedded in the COR. Mutations in this target-binding pocket disrupt the interaction between Wdr47-NTD and Camsap3. Impairing Wdr47-Camsap interactions markedly reduces rescue effects of Wdr47 on CP-MTs and ciliary beat of Wdr47-deficient ependymal cells. Thus, Wdr47-NTD functions by recognizing a specific basic helical motif in Camsap proteins via its non-canonical COR, a target-binding site in LisH-CTLH-containing domains.
钙调蛋白调节的血影蛋白相关蛋白（Camsaps）与WD40重复序列47的N端结构域（Wdr47-NTD；具有LisH-CTLH基序）结合，以正确生成轴丝中央微管（CP-MTs），从而实现哺乳动物活动多纤毛的平面摆动模式。然而，其潜在的分子机制仍不清楚。在这里，我们确定了游离的Wdr47-NTD以及与来自Camsap3的特征性Wdr47结合区域（WBR）形成复合物的Wdr47-NTD的结构。Wdr47-NTD除了典型的LisH和球状α螺旋核心（GAC）外，还形成了一个带有特殊交叉区域（COR）的交织二聚体。碱性WBR肽呈α螺旋构象，并锚定在COR中一个特制的酸性口袋中。这个靶点结合口袋中的突变破坏了Wdr47-NTD与Camsap3之间的相互作用。削弱Wdr47与Camsap的相互作用会显著降低Wdr47对CP-MTs的拯救作用以及对Wdr47缺陷的室管膜细胞纤毛摆动的影响。因此，Wdr47-NTD通过其非典型的COR识别Camsap蛋白中的特定碱性螺旋基序来发挥功能，COR是含LisH-CTLH结构域中的一个靶点结合位点。
