Microtubule assembly in cold-adapted organisms: Functional properties and structural adaptations of tubulins from Antarctic fishes
Microtubule assembly in cold-adapted organisms: Functional properties and structural adaptations of tubulins from Antarctic fishes
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DOI：
10.1016/s0300-9629(97)00012-1
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发表时间：
1997-11-01
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影响因子：
--
通讯作者：
Detrich, HW
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文献类型：
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作者：
Detrich, HW
原产于南极沿海沃茨的鱼类已经适应了-1.8至+2摄氏度的栖息地和体温。它们的细胞质微管，不像哺乳动物和温带变温动物，已经进化到在这些低温下有效地组装。为了了解潜在的分子适应，我的实验室正在研究微管蛋白[微管蛋白α β二聚体和微管相关蛋白（MAP）]和几种南极鱼类的微管蛋白基因，包括rockcods Notothenia coriicepts和Gobionotothen gibberifrons。我们发现，装配增强适应的鱼微管蛋白是固有的微管蛋白亚基本身。此外，南极鱼微管蛋白的微管形成是强烈的熵驱动，部分原因是增加的依赖，相对于其他物种的微管蛋白，疏水相互作用。微管蛋白多肽和cDNA的分析的基础上，我们认为，南极鱼微管蛋白的结构适应最有可能涉及微管蛋白同种型的主要序列的改变。对于来自其它脊椎动物的神经β微管蛋白，例如，N. Coriiceps脑在其446个残基的一级序列中含有七个独特的氨基酸取代和一个新的插入。这些变化中的大多数位于在微管组装期间形成微管蛋白二聚体之间的接触的结构域中，并且预期将增强多肽柔性，从而促进微管蛋白添加到微管末端。相比之下，α和β微管蛋白的酸性羧基末端尾部似乎不是聚合的冷适应位点。我们还发现，大脑和卵微管蛋白从南极鱼，其聚合效率，这表明，在协议与多微管蛋白假说，组织特异性微管蛋白亚型可以具有不同的功能特性显着不同。因此，微管蛋白的研究，从生物体，如南极鱼，已经适应了极端的热制度，应有助于显着的理解，控制微管组装在所有真核生物的第四纪相互作用。(C)1997年爱思唯尔科学公司
Fishes native to the coastal waters of the Antarctic have adapted to habitat and body temperatures in the range -1.8 to +2 degrees C. Their cytoplasmic microtubules, unlike those of mammals and temperate poikilotherms, have evolved to assemble efficiently at these low temperatures. To learn about the underlying molecular adaptations, my laboratory is studying microtubule proteins [tubulin alpha beta dimers and microtubule-associated proteins (MAPs)] and tubulin genes from several Antarctic fishes, including the rockcods Notothenia coriicepts and Gobionotothen gibberifrons. We find that the assembly-enhancing adaptations of the fish microtubule proteins are intrinsic to the tubulin subunits themselves. Furthermore, microtubule formation by Antarctic fish tubulins is strongly entropy driven, due in part-to an increased reliance, relative to tubulins from other species, on hydrophobic interactions. Based on analyses of tubulin polypeptides and cDNAs, we suggest that the structural adaptations of Antarctic fish tubulins most likely involve alterations in the primary sequences of tubulin isotypes. With respect to neural beta tubulins from other vertebrates, for example, the class II beta-tubulin isotype of N. coriiceps brain contains seven unique amino acid substitutions and one novel insertion in its 446-residue primary sequence. Most of these changes are located in a structural domain that forms contacts between tubulin dimers during microtubule assembly and would be expected to enhance polypeptide flexibility, thereby facilitating addition of tubulin to microtubule ends. The acidic carboxy-terminal tails of the alpha and beta tubulins, by contrast, appear not to be sites of cold adaptation of polymerization. We have also found that brain and egg tubulins from Antarctic fishes differ strikingly in their polymerization efficiencies, which demonstrates, in agreement with the multitubulin hypothesis, that tissue-specific tubulin isoforms can possess distinct functional properties. Thus, study of microtubule proteins from organisms, such as the Antarctic fishes, that have adapted to extreme thermal regimes should contribute significantly to an understanding of the quaternary interactions that control microtubule assembly in all eukaryotes. (C) 1997 Elsevier Science Inc.