Bundy J G, Kille P
Department of Surgery and Cancer, Imperial College London, Sir Alexander Fleming Building, London SW7 2AZ, UK.
Metallomics. 2014 Sep;6(9):1576-82. doi: 10.1039/c4mt00078a.
Phytochelatins are sulfur-rich metal-binding peptides, and phytochelatin synthesis is one of the key mechanisms by which plants protect themselves against toxic soft metal ions such as cadmium. It has been known for a while now that some invertebrates also possess functional phytochelatin synthase (PCS) enzymes, and that at least one species, the nematode Caenorhabditis elegans, produces phytochelatins to help detoxify cadmium, and probably also other metal and metalloid ions including arsenic, zinc, selenium, silver, and copper. Here, we review recent studies on the occurrence, utilization, and regulation of phytochelatin synthesis in invertebrates. The phytochelatin synthase gene has a wide phylogenetic distribution, and can be found in species that cover almost all of the animal tree of life. The evidence to date, though, suggests that the occurrence is patchy, and even though some members of particular taxonomic groups may contain PCS genes, there are also many species without these genes. For animal species that do possess PCS genes, some of them (e.g. earthworms) do synthesize phytochelatins in response to potentially toxic elements, whereas others (e.g. Schistosoma mansoni, a parasitic helminth) do not appear to do so. Just how (and if) phytochelatins in invertebrates complement the function of metallothioneins remains to be elucidated, and the temporal, spatial, and metal specificity of the two systems is still unknown.
植物螯合肽是富含硫的金属结合肽，植物螯合肽的合成是植物保护自身免受镉等有毒软金属离子侵害的关键机制之一。一段时间以来人们已经知道，一些无脊椎动物也拥有功能性的植物螯合肽合酶（PCS），并且至少有一种物种，即线虫秀丽隐杆线虫，会产生植物螯合肽来帮助镉解毒，可能还包括其他金属和类金属离子，如砷、锌、硒、银和铜。在此，我们综述了关于无脊椎动物中植物螯合肽合成的发生、利用和调控的最新研究。植物螯合肽合酶基因具有广泛的系统发育分布，几乎可以在涵盖动物生命树的所有物种中找到。然而，迄今为止的证据表明，其分布并不连续，尽管特定分类群的一些成员可能含有PCS基因，但也有许多物种没有这些基因。对于确实拥有PCS基因的动物物种，其中一些（如蚯蚓）会响应潜在有毒元素而合成植物螯合肽，而其他一些（如寄生蠕虫曼氏血吸虫）似乎不会这样做。无脊椎动物中的植物螯合肽如何（以及是否）补充金属硫蛋白的功能仍有待阐明，并且这两个系统的时间、空间和金属特异性仍然未知。
