Department of Genetics, Faculty of Biology, University of Barcelona, Av. Diagonal 645, 08028 Barcelona, Spain.
J Inorg Biochem. 2011 Aug;105(8):1050-9. doi: 10.1016/j.jinorgbio.2011.05.004. Epub 2011 May 19.
Metallothioneins (MTs) are a superfamily of Cys-rich polypeptides that bind heavy metal ions, both for physiological and detoxification purposes. They are present in all organisms, but their origin is probably polyphyletic, so that MT evolutionary studies are rather scarce. We present a thorough search and analysis of the MT coding sequences in the 12 Drosophila genomes completely sequenced, taking as reference the features reported for D. melanogaster, where four isogenes (MtnA to MtnD) are known and deeply characterized. We include a fifth isoform in this study, named MtnE, and recently annotated. The MTs polymorphism pattern is essentially the same for the 12 Drosophila species. Invariably, a MtnA form and an MtnB-cluster, comprising the MtnB-to-MtnE forms in tandem array, are observed. The whole set of genes are kept in the same synteny element (Muller E), but implicated in rearrangement events (mainly inversions), encompassing all or some of the isogenes. Gene exon/intron architecture, and cDNA and protein sequences appear highly conserved through Drosophila speciation, concordantly with an essential function for MT isoforms in flies, even for those previously considered as minor products. Data presented here will be comprehensively analyzed to provide a valuable guide for future MT evolutionary, structure and function studies.
金属硫蛋白（MTs）是富含半胱氨酸的多肽超家族，可结合重金属离子，兼具生理和解毒功能。它们存在于所有生物体中，但起源可能是多系的，因此 MT 的进化研究相当匮乏。我们对已完全测序的 12 个果蝇基因组中的 MT 编码序列进行了全面搜索和分析，以 D. melanogaster 报告的特征作为参考，其中已知并深入研究了四个同工基因（MtnA 到 MtnD）。在本研究中，我们包括了第五个同工基因 MtnE，它是最近被注释的。12 种果蝇的 MTs 多态性模式基本相同。始终观察到 MtnA 形式和 MtnB 簇，后者由串联排列的 MtnB 到 MtnE 形式组成。整套基因都保留在相同的基因座元件（ Muller E ）中，但涉及到重排事件（主要是倒位），包括所有或部分同工基因。通过果蝇种间进化，基因外显子/内含子结构、cDNA 和蛋白质序列表现出高度保守性，这与 MT 同工型在果蝇中的重要功能一致，即使对于那些以前被认为是次要产物的同工型也是如此。这里呈现的数据将进行全面分析，为未来的 MT 进化、结构和功能研究提供有价值的指导。
