title: The FinR-regulated essential gene fprA, encoding ferredoxin NADP+ reductase: Roles in superoxide-mediated stress protection and virulence of Pseudomonas aeruginosa.
abstract: Pseudomonas aeruginosa has two genes encoding ferredoxin NADP(+) reductases, denoted fprA and fprB. We show here that P. aeruginosa fprA is an essential gene. However, the ΔfprA mutant could only be successfully constructed in PAO1 strains containing an extra copy of fprA on a mini-Tn7 vector integrated into the chromosome or carrying it on a temperature-sensitive plasmid. The strain containing an extra copy of the ferredoxin gene (fdx1) could suppress the essentiality of FprA. Other ferredoxin genes could not suppress the requirement for FprA, suggesting that Fdx1 mediates the essentiality of FprA. The expression of fprA was highly induced in response to treatments with a superoxide generator, paraquat, or sodium hypochlorite (NaOCl). The induction of fprA by these treatments depended on FinR, a LysR-family transcription regulator. In vivo and in vitro analysis suggested that oxidized FinR acted as a transcriptional activator of fprA expression by binding to its regulatory box, located 20 bases upstream of the fprA -35 promoter motif. This location of the FinR box also placed it between the -35 and -10 motifs of the finR promoter, where the reduced regulator functions as a repressor. Under uninduced conditions, binding of FinR repressed its own transcription but had no effect on fprA expression. Exposure to paraquat or NaOCl converted FinR to a transcriptional activator, leading to the expression of both fprA and finR. The ΔfinR mutant showed an increased paraquat sensitivity phenotype and attenuated virulence in the Drosophila melanogaster host model. These phenotypes could be complemented by high expression of fprA, indicating that the observed phenotypes of the ΔfinR mutant arose from the inability to up-regulate fprA expression. In addition, increased expression of fprB was unable to rescue essentiality of fprA or the superoxide-sensitive phenotype of the ΔfinR mutant, suggesting distinct mechanisms of the FprA and FprB enzymes.
authors.affiliation: Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand.
authors.forename: Siriwan
authors.initials: S
authors.lastname: Boonma
authors.affiliation: Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand.
authors.forename: Adisak
authors.initials: A
authors.lastname: Romsang
authors.affiliation: Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand.
authors.forename: Jintana
authors.initials: J
authors.lastname: Duang-Nkern
authors.affiliation: Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand.
authors.forename: Sopapan
authors.initials: S
authors.lastname: Atichartpongkul
authors.affiliation: Department of Biology, Faculty of Science, Mahidol University, Bangkok, Thailand.
authors.forename: Wachareeporn
authors.initials: W
authors.lastname: Trinachartvanit
authors.affiliation: Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand.|Center of Excellence on Environmental Health and Toxicology, CHE, Ministry Of Education, Bangkok, Thailand.|Program in Applied Biological Sciences: Environmental Health, Chulabhorn Graduate Institute, Bangkok, Thailand.
authors.forename: Paiboon
authors.initials: P
authors.lastname: Vattanaviboon
authors.affiliation: Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand.|Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand.|Center of Excellence on Environmental Health and Toxicology, CHE, Ministry Of Education, Bangkok, Thailand.|Center for Emerging Bacterial Infections, Faculty of Science, Mahidol University, Bangkok, Thailand.
authors.forename: Skorn
authors.identifier: http://orcid.org/0000-0001-9698-0004
authors.initials: S
authors.lastname: Mongkolsuk
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D004330:Drosophila / Q000382:microbiology; D005287:Ferredoxin-NADP Reductase / Q000235:genetics* / Q000378:metabolism; D005288:Ferredoxins / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D018384:Oxidative Stress; D010641:Phenotype; D011550:Pseudomonas aeruginosa / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity; D013481:Superoxides / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014774:Virulence / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D005288:Ferredoxins; D014157:Transcription Factors; D013481:Superoxides; D005287:Ferredoxin-NADP Reductase