Evolution of the 2'-5'-Oligoadenylate Synthetase Family in Eukaryotes and Bacteria
Evolution of the 2'-5'-Oligoadenylate Synthetase Family in Eukaryotes and Bacteria
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DOI：
10.1007/s00239-009-9299-1
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发表时间：
2009-12-01
影响因子：
3.9
通讯作者：
Justesen, Just
中科院分区：
文献类型：
--
作者：
Kjaer, Karina Hansen;Poulsen, Jesper Buchhave;Justesen, Just
2‘-5’-寡腺苷合成酶(OAS)属于核苷酸转移酶家族，包括聚(A)聚合酶和CCA加成酶。在哺乳动物和鸟类中，OAS在干扰素系统中发挥作用，但在海绵中也以活性形式存在，海绵中没有干扰素系统。鉴于这些观察，我们一直追求的想法是，OAS基因可能存在于其他后生动物和单细胞生物体中。我们已经在环节动物、软体动物、爬行动物、脊索动物和单细胞真核生物中发现了一些OAS1基因，并在细菌中发现了一个包含五个OAS特异基序的蛋白质家族。这表明了与OAS的特定关系。OAS基因的广泛分布使我们有可能推测OAS1基因是如何从共同的祖先进化到脊椎动物和后生动物的。此外，我们认为OASL可能是从软骨鱼类的祖先进化而来的，而OAS2和OAS3基因可能是从哺乳动物的祖先进化而来的。OAS蛋白在哺乳动物的干扰素系统中发挥作用。这个系统只在有颌骨的脊椎动物中发现。因此，我们认为，OAS的原始功能可能与其在干扰素系统中的功能不同，即使在编码蛋白质的OAS基因中，这种原始功能也是保留的，而蛋白质不具有2‘-5’-寡腺苷合成酶活性。
The 2'-5'-oligoadenylate synthetase (OAS) belongs to a nucleotidyl transferase family that includes poly(A) polymerases and CCA-adding enzymes. In mammals and birds, the OAS functions in the interferon system but it is also present in an active form in sponges, which are devoid of the interferon system. In view of these observations, we have pursued the idea that OAS genes could be present in other metazoans and in unicellular organisms as well. We have identified a number of OAS1 genes in annelids, mollusks, a cnidarian, chordates, and unicellular eukaryotes and also found a family of proteins in bacteria that contains the five OAS-specific motifs. This indicates a specific relationship to OAS. The wide distribution of the OAS genes has made it possible to suggest how the OAS1 gene could have evolved from a common ancestor to choanoflagellates and metazoans. Furthermore, we suggest that the OASL may have evolved from an ancestor of cartilaginous fishes, and that the OAS2 and the OAS3 genes evolved from a mammalian ancestor. OAS proteins function in the interferon system in mammals. This system is only found in jawed vertebrates. We therefore suggest that the original function of OAS may differ from its function in the interferon system, and that this original function of OAS is preserved even in OAS genes that code for proteins, which do not have 2'-5'-oligoadenylate synthetase activity.