Gandara Ana Caroline Paiva, Torres André, Bahia Ana Cristina, Oliveira Pedro L, Schama Renata
Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
Laboratório de Biologia Computacional e Sistemas, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brazil.
BMC Evol Biol. 2017 Mar 29;17(1):92. doi: 10.1186/s12862-017-0940-0.
NADPH oxidases (NOX) are ROS producing enzymes that perform essential roles in cell physiology, including cell signaling and antimicrobial defense. This gene family is present in most eukaryotes, suggesting a common ancestor. To date, only a limited number of phylogenetic studies of metazoan NOXes have been performed, with few arthropod genes. In arthropods, only NOX5 and DUOX genes have been found and a gene called NOXm was found in mosquitoes but its origin and function has not been examined. In this study, we analyzed the evolution of this gene family in arthropods. A thorough search of genomes and transcriptomes was performed enabling us to browse most branches of arthropod phylogeny.
We have found that the subfamilies NOX5 and DUOX are present in all arthropod groups. We also show that a NOX gene, closely related to NOX4 and previously found only in mosquitoes (NOXm), can also be found in other taxonomic groups, leading us to rename it as NOX4-art. Although the accessory protein p22-phox, essential for NOX1-4 activation, was not found in any of the arthropods studied, NOX4-art of Aedes aegypti encodes an active protein that produces HO. Although NOX4-art has been lost in a number of arthropod lineages, it has all the domains and many signature residues and motifs necessary for ROS production and, when silenced, HO production is considerably diminished in A. aegypti cells.
Combining all bioinformatic analyses and laboratory work we have reached interesting conclusions regarding arthropod NOX gene family evolution. NOX5 and DUOX are present in all arthropod lineages but it seems that a NOX2-like gene was lost in the ancestral lineage leading to Ecdysozoa. The NOX4-art gene originated from a NOX4-like ancestor and is functional. Although no p22-phox was observed in arthropods, there was no evidence of neo-functionalization and this gene probably produces HO as in other metazoan NOX4 genes. Although functional and present in the genomes of many species, NOX4-art was lost in a number of arthropod lineages.
NADPH氧化酶（NOX）是产生活性氧（ROS）的酶，在细胞生理学中发挥重要作用，包括细胞信号传导和抗菌防御。这个基因家族存在于大多数真核生物中，表明有一个共同的祖先。迄今为止，仅对后生动物的NOX进行了有限数量的系统发育研究，涉及的节肢动物基因很少。在节肢动物中，仅发现了NOX5和DUOX基因，并且在蚊子中发现了一个名为NOXm的基因，但其起源和功能尚未得到研究。在本研究中，我们分析了该基因家族在节肢动物中的进化。我们对基因组和转录组进行了全面搜索，从而能够浏览节肢动物系统发育的大多数分支。
我们发现NOX5和DUOX亚家族存在于所有节肢动物类群中。我们还表明，一个与NOX4密切相关且以前仅在蚊子中发现的NOX基因（NOXm），也可以在其他分类群中找到，因此我们将其重新命名为NOX4-art。尽管在任何研究的节肢动物中均未发现对NOX1-4激活至关重要的辅助蛋白p22-phox，但埃及伊蚊的NOX4-art编码一种产生HO的活性蛋白。尽管NOX4-art在许多节肢动物谱系中已经丢失，但它具有产生ROS所需的所有结构域以及许多特征性残基和基序，并且在沉默时，埃及伊蚊细胞中的HO产生会大大减少。
综合所有生物信息学分析和实验室工作，我们得出了有关节肢动物NOX基因家族进化的有趣结论。NOX5和DUOX存在于所有节肢动物谱系中，但似乎一个类似NOX2的基因在导致蜕皮动物的祖先谱系中丢失了。NOX4-art基因起源于一个类似NOX4的祖先并且具有功能。尽管在节肢动物中未观察到p22-phox，但没有新功能化的证据，并且该基因可能像其他后生动物NOX4基因一样产生HO。尽管具有功能且存在于许多物种的基因组中，但NOX4-art在许多节肢动物谱系中已经丢失。
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