Untangling spider silk evolution with spidroin terminal domains.
Untangling spider silk evolution with spidroin terminal domains.
复制标题
DOI：
10.1186/1471-2148-10-243
复制
发表时间：
2010-08-09
影响因子：
3.4
通讯作者：
Hayashi CY
中科院分区：
文献类型：
--
作者：
Garb JE;Ayoub NA;Hayashi CY
蛛丝蛋白是一个独特的大家族，结构蛋白质，构成了蜘蛛丝纤维的主体。由于其重复序列的高度可变性，蛛丝蛋白的进化关系主要是从其非重复羧基（C）末端结构域确定的，尽管它们提供的特征数据有限。少数已知的蛛丝蛋白氨基（N）末端结构域已经很难获得，但可能包含关键的系统发育信息重建蜘蛛丝的多样化。在这里，我们使用的丝腺表达数据（EST）从高度分化的物种，以评估功能的意义和系统发育效用的蛛丝蛋白N-末端结构域。我们报告了通过对来自9种蜘蛛物种的约1，900个丝腺cDNA进行测序发现的另外11个蛛丝N末端，这些蜘蛛物种在2.4亿年前拥有共同的祖先。与它们的高变重复区相反，蛛丝蛋白N-末端结构域在序列同一性、预测的二级结构和疏水性方面保留了惊人的相似性。通过单独和合并的N-末端结构域及其相应的C-末端的系统发育分析，我们发现，联合分析产生的最解决的树，N-末端贡献更多的支持和较少的冲突比C-末端。这些分析表明，旁系同源物主要组的丝腺类型，除了大壶腹状蛛丝。此外，蜘蛛丝蛋白结构图案与上级抗张强度出现在这个基因家族的历史早期，而一个图案赋予更大的可扩展性收敛进化在两个远亲旁系。非重复的N-末端结构域似乎是蛛丝蛋白的普遍属性，可能从蜘蛛丝产生的起源保留下来。从那时起，蛛丝蛋白N-末端保持了几个特征，与该结构域在丝组装中起关键作用一致。保守的N-和C-末端结构域的系统发育分析说明了蜘蛛丝蛋白基因家族的巨大辐射，涉及广泛的重复，表达模式的变化和极端多样化的重复结构序列，赋予蜘蛛丝无与伦比的机械性能。
Spidroins are a unique family of large, structural proteins that make up the bulk of spider silk fibers. Due to the highly variable nature of their repetitive sequences, spidroin evolutionary relationships have principally been determined from their non-repetitive carboxy (C)-terminal domains, though they offer limited character data. The few known spidroin amino (N)-terminal domains have been difficult to obtain, but potentially contain critical phylogenetic information for reconstructing the diversification of spider silks. Here we used silk gland expression data (ESTs) from highly divergent species to evaluate the functional significance and phylogenetic utility of spidroin N-terminal domains. We report 11 additional spidroin N-termini found by sequencing ~1,900 silk gland cDNAs from nine spider species that shared a common ancestor > 240 million years ago. In contrast to their hyper-variable repetitive regions, spidroin N-terminal domains have retained striking similarities in sequence identity, predicted secondary structure, and hydrophobicity. Through separate and combined phylogenetic analyses of N-terminal domains and their corresponding C-termini, we find that combined analysis produces the most resolved trees and that N-termini contribute more support and less conflict than the C-termini. These analyses show that paralogs largely group by silk gland type, except for the major ampullate spidroins. Moreover, spidroin structural motifs associated with superior tensile strength arose early in the history of this gene family, whereas a motif conferring greater extensibility convergently evolved in two distantly related paralogs. A non-repetitive N-terminal domain appears to be a universal attribute of spidroin proteins, likely retained from the origin of spider silk production. Since this time, spidroin N-termini have maintained several features, consistent with this domain playing a key role in silk assembly. Phylogenetic analyses of the conserved N- and C-terminal domains illustrate dramatic radiation of the spidroin gene family, involving extensive duplications, shifts in expression patterns and extreme diversification of repetitive structural sequences that endow spider silks with an unparalleled range of mechanical properties.
登录
查看更多内容
影响因子：
2.6
作者：
Gaines WA 4th;Marcotte WR Jr
通讯作者：
Marcotte WR Jr
影响因子：
3.6
作者：
Gatesy, J;O'Grady, P;Baker, RH
通讯作者：
Baker, RH
影响因子：
5.6
作者：
GARNIER, J;OSGUTHORPE, DJ;ROBSON, B
通讯作者：
ROBSON, B
影响因子：
2.7
作者：
Beuken, E;Vink, C;Bruggeman, CA
通讯作者：
Bruggeman, CA
影响因子：
5.6
作者：
Hayashi, CY;Lewis, RV
通讯作者：
Lewis, RV