Metallothioneins (MTs) are proteins devoted to the control of metal homeostasis and detoxification, and therefore, MTs have been crucial for the adaptation of the living beings to variable situations of metal bioavailability. The evolution of MTs is, however, not yet fully understood, and to provide new insights into it we have investigated the MTs in the diverse classes of Molluscs. We have shown that most molluscan MTs are bi-modular proteins that combine six domains –α, β1, β2, β3, γ and δ– in a lineage specific manner. We have functionally characterized the Neritimorpha β₃β₁ and the Patellogastropoda γβ₁ MTs, demonstrating the metal-binding capacity of the new γ domain. Our results have revealed a modular organization of mollusc MT, whose evolution has been impacted by duplication, loss and de novo emergence of domains. MTs represent a paradigmatic example of modular evolution probably driven by the structural and functional requirements of metal binding.

中文翻译：

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蛋白质进化的模块性：软体动物金属硫蛋白的模块化组织和从头结构域进化。

金属硫蛋白（MTs）是致力于控制金属稳态和排毒的蛋白质，因此，MTs对于生物适应各种金属生物利用度状况至关重要。但是，对MT的演变尚未完全了解，为了提供新的见解，我们研究了软体动物不同类别的MT。我们已经表明，大多数软体动物MT是双模块蛋白，它们以谱系特异性方式结合六个域–α，β1，β2，β3，γ和δ。我们已经在功能上表征了Neritimorphaβ ₃ β ₁和笠形腹足亚纲γβ ₁MT，证明了新的γ域的金属结合能力。我们的研究结果揭示了软体动物MT的模块化组织，其发展受到域的重复，丢失和从头出现的影响。MTs代表了模块化演变的典范范例，可能是由金属结合的结构和功能要求驱动的。