Bower Raqual, VanderWaal Kristyn, O'Toole Eileen, Fox Laura, Perrone Catherine, Mueller Joshua, Wirschell Maureen, Kamiya R, Sale Winfield S, Porter Mary E
Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455, USA.
Mol Biol Cell. 2009 Jul;20(13):3055-63. doi: 10.1091/mbc.e09-04-0277. Epub 2009 May 6.
To understand the mechanisms that regulate the assembly and activity of flagellar dyneins, we focused on the I1 inner arm dynein (dynein f) and a null allele, bop5-2, defective in the gene encoding the IC138 phosphoprotein subunit. I1 dynein assembles in bop5-2 axonemes but lacks at least four subunits: IC138, IC97, LC7b, and flagellar-associated protein (FAP) 120--defining a new I1 subcomplex. Electron microscopy and image averaging revealed a defect at the base of the I1 dynein, in between radial spoke 1 and the outer dynein arms. Microtubule sliding velocities also are reduced. Transformation with wild-type IC138 restores assembly of the IC138 subcomplex and rescues microtubule sliding. These observations suggest that the IC138 subcomplex is required to coordinate I1 motor activity. To further test this hypothesis, we analyzed microtubule sliding in radial spoke and double mutant strains. The results reveal an essential role for the IC138 subcomplex in the regulation of I1 activity by the radial spoke/phosphorylation pathway.
为了了解调节鞭毛动力蛋白组装和活性的机制，我们聚焦于I1内臂动力蛋白（动力蛋白f）以及一个无效等位基因bop5 - 2，该等位基因在编码IC138磷蛋白亚基的基因中存在缺陷。I1动力蛋白在bop5 - 2轴丝中组装，但至少缺少四个亚基：IC138、IC97、LC7b和鞭毛相关蛋白（FAP）120，从而定义了一个新的I1亚复合体。电子显微镜和图像平均分析显示，在I1动力蛋白基部、径向辐条1和外动力蛋白臂之间存在缺陷。微管滑动速度也降低。用野生型IC138进行转化可恢复IC138亚复合体的组装并挽救微管滑动。这些观察结果表明，IC138亚复合体是协调I1马达活性所必需的。为了进一步验证这一假设，我们分析了径向辐条和双突变体菌株中的微管滑动。结果揭示了IC138亚复合体在通过径向辐条/磷酸化途径调节I1活性中起着至关重要的作用。
