MULTIPLE NUCLEOTIDE-BINDING SITES IN THE SEQUENCE OF DYNEIN BETA-HEAVY CHAIN
MULTIPLE NUCLEOTIDE-BINDING SITES IN THE SEQUENCE OF DYNEIN BETA-HEAVY CHAIN
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DOI：
10.1038/352640a0
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发表时间：
1991-08-15
期刊：
影响因子：
64.8
通讯作者：
ASAI, DJ
中科院分区：
文献类型：
--
作者：
GIBBONS, IR;GIBBONS, BH;ASAI, DJ
轴突动力蛋白具有两个或三个球形头部，通过柔性尾部连接到共同的碱基，每个头部/尾部单元由相对分子质量> 400，000的单个重链多肽组成。通过电子显微镜1-3推导出组分的尺寸。海胆精子鞭毛的分离β重链在免疫学上与胚胎纤毛相同（数据未显示;参考文献4），特别令人感兴趣，因为它保留了体外微管移位的能力5，6。β-重链的有限蛋白水解将其分为两个片段A和B，分别沉淀在12 S和6 S处，可能对应于分子7的头部和尾部结构域。动力蛋白ATP酶是一种能量转换酶，它产生小管之间的滑动运动，这是真核生物纤毛和鞭毛跳动的基础，也可能是其他大的细胞内运动8，9。在这里，我们报告，推导的氨基酸序列的β-重链的轴丝动力蛋白从胚胎的海胆Tripneustes gratilla有4,466个残基，并包含5个核苷酸结合位点的共识模体。可能的水解ATP结合位点可以通过其位置接近或位于钒酸盐介导的光裂解的V1位点来鉴定10。先前报道的光裂解和蛋白水解肽的图的一般特征已经被证实，除了图的极性被反转。β-重链的预测二级结构由沿着其整个长度的α/β型模式组成。潜在的α螺旋的两个最长的区域，具有120和50个氨基酸长的未断裂的七肽疏水重复序列，可能具有功能重要性。但动力蛋白似乎不包含一个扩展的卷曲螺旋尾域。
AXONEMAL dyneins have two or three globular heads joined by flexible tails to a common base, with each head/tail unit consisting of a single heavy-chain polypeptide of relative molecular mass > 400,000. The sizes of the components have been deduced by electron microscopy 1-3 . The isolated-beta heavy chain of sea urchin sperm flagella, which is immunologically identical to that of the embryo cilia (data not shown; ref. 4), is of particular interest as it retains the capability for microtubule translocation in vitro 5,6. Limited proteolysis of the beta-heavy chain divides it into two fragments, A and B, which sediment separately at 12S and 6S, and possibly correspond to the head and tail domains of the molecule 7. Dynein ATPase is the energy-transducing enzyme that generates the sliding movement between tubules that underlies the beating of cilia and flagella of eukaryotes, and possibly also other large intracellular movements 8,9. Here we report that the deduced amino-acid sequence of the beta-heavy chain of axonemal dynein from embryos of the sea urchin Tripneustes gratilla has 4,466 residues and contains the consensus motifs for five nucleotide-binding sites. The probable hydrolytic ATP-binding site can be identified by its location close to or at the V1 site of vanadate-mediated photocleavage 10. The general features of the map of photocleavage and proteolytic peptides reported earlier have been confirmed, except that the map's polarity is reversed. The predicted secondary structure of the beta-heavy chain consists of an alpha/beta-type pattern along its whole length. The two longest regions of potential alpha helix, with unbroken heptad hydrophobic repeats 120 and 50 amino acids long, may be of functional importance. But dynein does not seem to contain an extended coiled-coil tail domain.