The hemocyanin from a living fossil, the cephalopod Nautilus pompilius:: Protein structure, gene organization, and evolution
The hemocyanin from a living fossil, the cephalopod Nautilus pompilius:: Protein structure, gene organization, and evolution
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DOI：
10.1007/s00239-005-0160-x
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发表时间：
2006-03-01
影响因子：
3.9
通讯作者：
Markl, J
中科院分区：
文献类型：
--
作者：
Bergmann, S;Lieb, B;Markl, J
通过电子显微镜和免疫生物化学分析，我们已经证实了早期的证据，即鹦鹉螺血蓝蛋白（NPH）是一个环状十聚体（M-r =类似于350万），组装从10个相同的拷贝类似于350 kDa的多肽。该亚基又被亚结构化为七个顺序的共价连接的功能单元，每个功能单元类似于50 kDa（FU a-g）。我们克隆并测序了编码该多肽的cDNA，其全长为9198 bp，其中5'端UTR为58 bp，3'端UTR为365 bp，开放阅读框为21个氨基酸的信号肽和2903个氨基酸的多肽（Mr = 335，881）。根据序列比对，鹦鹉螺血蓝蛋白的七个FU直接对应于来自头足类章鱼dofleini的先前测序的血蓝蛋白“ODH”的七个FU类型。十三个潜在的N-糖基化位点分布在七个鹦鹉螺血蓝蛋白FU的pueridine连接聚糖的结构后果进行了讨论的基础上发表的X射线结构的章鱼dofleini和红螺FU。此外，鹦鹉螺血蓝蛋白的完整基因结构进行了分析，它类似于章鱼血蓝蛋白的连接子内含子，但显示两个内部内含子，不同的位置从章鱼血蓝蛋白基因的三个内部内含子。多重序列比对可以计算出一个相当强大的系统发育树和一个统计上可靠的分子钟。这表明鹦鹉螺和章鱼最后的共同祖先生活在4.15亿+/-2400万年前，与泥盆纪早期的化石记录非常一致。
By electron microscopic and immunobiochemical analyses we have confirmed earlier evidence that Nautilus pompilius hemocyanin ( NpH) is a ring-like decamer ( M-r = similar to 3.5 million), assembled from 10 identical copies of an similar to 350-kDa polypeptide. This subunit in turn is substructured into seven sequential covalently linked functional units of similar to 50 kDa each ( FUs a-g). We have cloned and sequenced the cDNA encoding the complete polypeptide; it comprises 9198 bp and is subdivided into a 5' UTR of 58 bp, a 3' UTR of 365 bp, and an open reading frame for a signal peptide of 21 amino acids plus a polypeptide of 2903 amino acids ( Mr = 335,881). According to sequence alignments, the seven FUs of Nautilus hemocyanin directly correspond to the seven FU types of the previously sequenced hemocyanin "OdH'' from the cephalopod Octopus dofleini. Thirteen potential N-glycosylation sites are distributed among the seven Nautilus hemocyanin FUs; the structural consequences of putatively attached glycans are discussed on the basis of the published X-ray structure for an Octopus dofleini and a Rapana thomasiana FU. Moreover, the complete gene structure of Nautilus hemocyanin was analyzed; it resembles that of Octopus hemocyanin with respect to linker introns but shows two internal introns that differ in position from the three internal introns of the Octopus hemocyanin gene. Multiple sequence alignments allowed calculation of a rather robust phylogenetic tree and a statistically firm molecular clock. This reveals that the last common ancestor of Nautilus and Octopus lived 415 +/- 24 million years ago, in close agreement with fossil records from the early Devonian.