title: Evolutionary origin and function of NOX4-art, an arthropod specific NADPH oxidase.
abstract: 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 H2O2. 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, H2O2production 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 H2O2as 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.
authors.affiliation: Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil. acpgandara@gmail.com.
authors.forename: Ana Caroline Paiva
authors.initials: ACP
authors.lastname: Gandara
authors.affiliation: Laboratório de Biologia Computacional e Sistemas, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brazil.
authors.forename: André
authors.initials: A
authors.lastname: Torres
authors.affiliation: Instituto de Biofísica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Ana Cristina
authors.initials: AC
authors.lastname: Bahia
authors.affiliation: Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.|Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular - INCT-EM, Rio de Janeiro, Brazil.
authors.forename: Pedro L
authors.initials: PL
authors.lastname: Oliveira
authors.affiliation: Laboratório de Biologia Computacional e Sistemas, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brazil. schama@ioc.fiocruz.br.|Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular - INCT-EM, Rio de Janeiro, Brazil. schama@ioc.fiocruz.br.
authors.forename: Renata
authors.identifier: 0000-0003-1978-3757
authors.initials: R
authors.lastname: Schama
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001181:Arthropods / Q000201:enzymology* / Q000235:genetics*; D019143:Evolution, Molecular; D049750:Genome, Insect; D006861:Hydrogen Peroxide; D019255:NADPH Oxidases / Q000737:chemistry / Q000235:genetics*; D010802:Phylogeny; D017382:Reactive Oxygen Species; D016415:Sequence Alignment; D015398:Signal Transduction
chemical_list: D017382:Reactive Oxygen Species; D006861:Hydrogen Peroxide; D019255:NADPH Oxidases
keywords: Arthropods; Gene family; Gene loss; NADPH oxidase; ROS; Reactive oxygen species