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首页> 外文期刊>Cell motility and the cytoskeleton >Molecular structure of dynein and motility of a giant sperm axoneme provided with only the outer dynein arm.
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Molecular structure of dynein and motility of a giant sperm axoneme provided with only the outer dynein arm.

机译：动力蛋白的分子结构和仅装有动力蛋白外臂的巨型精子轴蛋白的运动性。

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The peculiar sperm axoneme of the dipteran Asphondylia ruebsaameni is characterized by an extraordinarily high number of microtubule doublets (up to 2,500) arranged in double parallel spirals. Doublets of the inner row of each spiral are tilted, so that their outer arms point towards the B-tubule of the next doublet in the outer row. Doublets are provided with only the outer arm, and no structure related to the central pair/radial spoke complex is present. When analyzed by quick-freeze, deep-etch electron microscopy, the structure of the dynein arms was shown to share the same organization described in other organisms; however, it appears to be somewhat more complex than that previously found in a related dipteran species, Monarthropalpus flavus, since the foot region of the arms displays a globular extra-domain that is intercalated between adjacent arms. Treatment of demembranated sperm with ATP and vanadate induced conformational changes in the dynein arms. SDS-page suggested the presence of a single dynein high molecular weight band or, in the gels with the best electrophoretic resolution, of two very closely spaced bands. This polypeptide positively reacted with a polyclonal antibody raised against a specific amino acid sequence located in the phosphate-binding loop of the dynein catalytic site. Dynein heavy chain-related DNA sequences corresponding to the catalytic phosphate-binding region were amplified by RT-PCR. Two distinct fragments (Asph-ax1 and Asph-ax2) encoding axonemal dynein sequences were identified. Southern blot analysis performed on genomic DNA using these sequences as a probe showed that they are part of different genes. An intron was identified in the Asph-ax1 fragment at a position corresponding to the site of a nucleotide deletion in the putative pseudogene of Monarthropalpus. Asphondylia spermatozoa exhibited in vivo a whirling movement both in the deferent duct and in the spermatheca, but they were unable to undergo processive movement in vitro. They propagated a three-dimensional wave only when constrained in a bent configuration by some mechanical means. The phylogenetic relationships between the two dipteran species, Monarthopalpus and Asphondylia, based on these biochemical and molecular data are also discussed.
机译：二倍体Asphondylia ruebsaameni特有的精子轴索蛋白的特征是，以双平行螺旋排列的微管双合子数量非常多（最多2,500个）。每个螺旋的内排的双胞胎都倾斜，因此它们的外臂指向外排中下一个双胞胎的B管。双联仅设有外臂，并且不存在与中央对/径向辐条复合体有关的结构。当通过快速冷冻，深蚀刻电子显微镜进行分析时，显示出达因臂的结构与其他生物体具有相同的组织。但是，它似乎比以前在相关的双足动物物种黄褐线虫（Monarthropalpus flavus）中发现的更为复杂，因为臂的脚部区域显示出球状的额外域，该域插入在相邻臂之间。用ATP和钒酸盐处理的去膜精子诱导达因素臂的构象变化。 SDS-page建议存在一个单独的达因高分子量带，或者在电泳分离度最高的凝胶中，存在两个非常紧密间隔的带。该多肽与多克隆抗体阳性反应，该多克隆抗体针对位于动力蛋白催化位点磷酸结合环中的特定氨基酸序列。通过RT-PCR扩增对应于催化磷酸结合区域的与动力蛋白重链相关的DNA序列。识别出两个不同的片段（Asph-ax1和Asph-ax2）编码轴索动力蛋白序列。使用这些序列作为探针对基因组DNA进行的Southern印迹分析表明，它们是不同基因的一部分。在Asph-ax1片段的一个对应于推定的Monarthropalpus假基因的核苷酸缺失位点的位置鉴定出一个内含子。体内的Asphondylia spermatozoa在输精管和精子中均表现出旋转运动，但它们无法在体外进行过程性运动。他们只有在通过某种机械手段以弯曲形态约束时才传播三维波。基于这些生化和分子数据，还讨论了两种二倍体物种Monarthopalpus和Asphondylia之间的系统发生关系。

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