Abstract
Cilia are deeply conserved eukaryotic organelles that are essential to proper embryonic development in vertebrates through their roles in motility and signaling. Both ciliary assembly (ciliogenesis) and the movement of cargo along the ciliary axoneme depend on intraflagellar transport (IFT), which is executed through a super-assembly of motor proteins and cargo adaptors. The IFT core complexes, IFT-A and IFT-B, are hotspots for disease variants that lead to ciliopathies, genetic diseases resulting from ciliary dysfunction. To date, the structures of many IFT-associated protein complexes have yet to be well-characterized. Here, we combined chemical cross-linking mass spectrometry of intact complexes, AlphaFold2-predicted protein structures, and cryo-electron tomography to perform integrative modeling to define the overall architecture of the 6-subunit IFT-A complex. Crucially, our model is consistent with a wide array of existing biochemical data. The packing of IFT-A highlights preferred interaction modes made by proteins exhibiting similar domain architectures. We use this model to provide insights into the pleiotropic nature of genetic variants in IFT-A that are associated with human ciliopathies. Our work demonstrates the power of integrative modeling both for multi-protein structure determination and for understanding the etiology of human genetic disease.
Competing Interest Statement
The authors have declared no competing interest.