Differential light chain assembly influences outer arm dynein motor function
Differential light chain assembly influences outer arm dynein motor function
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DOI：
10.1091/mbc.e05-08-0732
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发表时间：
2005-12-01
影响因子：
3.3
通讯作者：
King, SM
中科院分区：
文献类型：
--
作者：
DiBella, LM;Gorbatyuk, O;King, SM
Tctex 1和Tctex 2最初被描述为小鼠t单倍型非孟德尔传递中的潜在扭曲因子/不育因子。这些蛋白质已被鉴定为细胞质和/或轴丝动力蛋白的亚基。在衣原体鞭毛内，Tctex 1是内臂I1的亚基。我们现在已经确定了第二个Tctex 1相关蛋白（这里称为LC 9）在衣原体。LC 9在蔗糖密度梯度中与外臂动力蛋白共纯化，并且仅在完全缺乏该马达的那些菌株中缺失。纯化的外臂动力蛋白的零长度交联表明LC 9直接与IC 1和IC 2中间链相互作用。免疫印迹分析显示，LC 2，LC 6和LC 9在IC 2突变株（oda 6-r88）中缺失，该突变株可以组装外臂，但表现出明显降低的鞭毛跳动频率。这种缺陷不太可能是由于缺乏LC 6，因为LC 6无效突变体（oda 13）仅表现出轻微的游泳异常。使用LC 2无效突变体（oda 12 -1），我们发现，虽然一些外臂动力蛋白组件组装在LC 2的情况下，他们是无功能的。相比之下，来自oda 6-r88的动力蛋白，也缺乏LC 2，保留了一些活性。此外，我们观察到一个oda 6-r88 oda 12 -1双突变体的合成装配缺陷。这些数据表明，LC 2，LC 6和LC 9在外臂组装中具有不同的作用，并且是衣原体鞭毛中野生型运动功能所需的。
Tctex1 and Tctex2 were originally described as potential distorters/sterility factors in the non-Mendelian transmission of t-haplotypes in mice. These proteins have since been identified as subunits of cytoplasmic and/or axonemal dyneins. Within the Chlamydomonas flagellum, Tctex1 is a subunit of inner arm I1. We have now identified a second Tctex1-related protein (here termed LC9) in Chlamydomonas. LC9 copurifies with outer arm dynein in sucrose density gradients and is missing only in those strains completely lacking this motor. Zero-length cross-linking of purified outer arm dynein indicates that LC9 interacts directly with both the IC1 and IC2 intermediate chains. Immunoblot analysis revealed that LC2, LC6, and LC9 are missing in an IC2 mutant strain (oda6-r88) that can assemble outer arms but exhibits significantly reduced flagellar beat frequency. This defect is unlikely to be due to lack of LC6, because an LC6 null mutant (oda13) exhibits only a minor swimming abnormality. Using an LC2 null mutant (oda12-1), we find that although some outer arm dynein components assemble in the absence of LC2, they are nonfunctional. In contrast, dyneins from oda6-r88, which also lack LC2, retain some activity. Furthermore, we observed a synthetic assembly defect in an oda6-r88 oda12-1 double mutant. These data suggest that LC2, LC6, and LC9 have different roles in outer arm assembly and are required for wild-type motor function in the Chlamydomonas flagellum.