Tubulin lattice in cilia is in a stressed form regulated by microtubule inner proteins
Tubulin lattice in cilia is in a stressed form regulated by microtubule inner proteins
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DOI：
10.1073/pnas.1911119116
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发表时间：
2019-10-01
影响因子：
11.1
通讯作者：
Bui，Khanh Huy
中科院分区：
文献类型：
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作者：
Ichikawa，Muneyoshi;Khalifa，Ahmad Abdelzaher Zaki;Bui，Khanh Huy
纤毛是毛发状的突起，以高频率跳动推动细胞或移动液体，由径向束状的双态微管组成。在这项研究中，我们提出了一个近原子分辨率的四膜双体微管的低温电子显微镜图。这张图表明微管内部蛋白质网络编织进微管晶格，形成一个内鞘。从质谱数据和从头建模中，我们确定了Rib43a蛋白是原丝带区域的丝状微管内部蛋白。rib43a -微管蛋白相互作用导致每2个二聚体的微管蛋白距离拉长。此外，经萨尔科齐处理缺失微管内蛋白（MIPs）的微管蛋白晶格结构在原丝间表现出明显的纵向压实和横向角度变化。这些结果证明了微管蛋白直接影响和稳定微管蛋白晶格。这表明，双态微管是一种内在的应力细丝，这种应力可以在纤毛波形的调节中被操纵。
Cilia, the hair-like protrusions that beat at high frequencies to propel a cell or move fluid around are composed of radially bundled doublet microtubules. In this study, we present a near-atomic resolution map of theTetrahymenadoublet microtubule by cryoelectron microscopy. The map demonstrates that the network of microtubule inner proteins weaves into the tubulin lattice and forms an inner sheath. From mass spectrometry data and de novo modeling, we identified Rib43a proteins as the filamentous microtubule inner proteins in the protofilament ribbon region. The Rib43a–tubulin interaction leads to an elongated tubulin dimer distance every 2 dimers. In addition, the tubulin lattice structure with missing microtubule inner proteins (MIPs) by sarkosyl treatment shows significant longitudinal compaction and lateral angle change between protofilaments. These results are evidence that the MIPs directly affect and stabilize the tubulin lattice. It suggests that the doublet microtubule is an intrinsically stressed filament and that this stress could be manipulated in the regulation of ciliary waveforms.